PlanetPapers.com RSS Feedhttps://www.planetpapers.com/ Maternal Exercise during Pregnancy Increases BDNF Levels and Cell Numbers in the Hippocampal Formation but Not in the Cerebral Cortex of Adult Rat Offspring 2017-12-22T02:02:08.717-05:00 http://75.150.148.189/free-essay/Maternal-Exercise-during-Pregnancy-Increases-BDNF-Levels-and-Cell-Numbers-in-the-Hippocampal-Formation-but-Not-in-the-Cerebral-Cortex-of-Adult-Rat-Offspring-7001.aspx The prime cause prevention and treatment of cancer 2017-01-19T16:06:09.89-05:00 http://75.150.148.189/free-essay/The-prime-cause-prevention-and-treatment-of-cancer-6970.aspx From the cranial sutures to the rib cage and beyond, surveying x-rays of anatomical parts of the human body has been a keen interest of mine. My anatomy class helped me realize that treating and diagnosing people through medicine would be the field I woul 2012-12-14T09:53:27.463-05:00 http://75.150.148.189/free-essay/From-the-cranial-sutures-to-the-rib-cage-and-beyond,-surveying-x-rays-of-anatomical-parts-of-the-human-body-has-been-a-keen-interest-of-mine_-My-anatomy-class-helped-me-realize-that-treating-and-diagnosing-people-through-medicine-would-be-the-field-I-woul-6869.aspx The Pros and Cons of Genetic Engineering (Cloning) Four billion years ago, life arose on the Earth. Four billion years later, human beings begin to look into the secrets hidden in genes, which are the most delicate structure of life. Scientists in recent years have completed the Human Genome Project, which is one of the three most important advances in scientific history. Cloning is the major technique developed in the research of genes. To clone means to make genetically identical copies. As for human cloning, it is achieved by putting the genetic material from a donor’s somatic cell into a woman‘s egg, which has already had its nucleus removed. That is to say, the cloning cells share the same genetic materials with the donor. When it comes to human cloning, people begin to diverse in their opinions. Some think human cloning as gift from God while the others regard it as the work of Satan. Bioethics, which is the study of value judgments pertaining to human conduct in the area of biology and includes those related to the practice of medicine, has been an important aspect of all areas in the scientific field (Bernstein, Maurice, M.D.). It is one of the factors that says whether or not certain scientific research can go on, and if it can, under which rules and regulations it must abide by. One of the most recent and controversial issues facing our society today is the idea of cloning. It is true that we are just on the brink of discovering all of the dangers and benefits of genetic engineering and there is a lot of important information that still remains unknown. But instead of seeing the immense potential benefits of this mind-boggling discovery, the American public - fed on science fiction novels, horror stories of environmental disaster, a “growing mistrust of science” (Nelkin 1), and the fear of the unknown – automatically reject this god sent breakthrough. In February of 1997, the biotechnology firm PPL Therapeutics in association with the Roslin Institute of Edinburgh, Scotland announced the first successful fully cloned mammal. They had cloned a lamb from an adult sheep, which they named Dolly after Dolly Parton (Mario,Christopher). The two shared the same nucleic DNA, but differed in terms of their mitochondrial DNA, which is vitally important for the regulation of the cell. The media and 2007-11-29T07:28:41-05:00 http://75.150.148.189/free-essay/The-Pros-and-Cons-of-Genetic-Engineering-Cloning-6792.aspx Investigation into the factors that effect rennin RESEARCH I know that Rennin is an enzyme, so before conducting this experiment I am first going to do some research into enzymes and their effects. 1. Enzymes Enzymes are large globular molecules of which the vast majority are protein in nature, though some, known as 'ribozymes' are made of RNA. Enzymes have catalytic properties; in other words, they alter the rate of reaction without themselves undergoing a permanent change. Most chemical reactions require an initial input of energy, called activation energy, to enable them to occur. Enzymes reduce the need for activation energy and so allow reactions to take place more readily and at lower temperatures than would otherwise be necessary. This can be seen in the graphs. 2. Enzyme Action Enzymes, as biological catalysts, can be used in both anabolism (the build up of simple chemicals into complex ones) and catabolism (the breakdown of complex chemicals into simpler ones), although the latter is more common especially in the animal digestive system. As shown in the next diagram it is thought that the substrate molecules fit precisely into the enzyme molecules. This theory is referred to as the lock and key mechanism. However, in practice, it is likely that the enzyme itself to some extent is the substrate. The part of the enzyme molecule into which the substrate fits is called the active site. The configuration of the enzyme is due to ionic bonding, hydrogen bonding, disulphide bridges and hydrophobic interactions. 3. Specificity The substrate molecule makes a precise fit into the active site and though the enzyme may be flexible up to a point, the number of molecules which can fit into the active site is very small - in fact it is often limited to just one type. Therefore enzymes are specific to one type of reaction. 4. Reversibility Enzymes can catalyse the forward and reverse reactions equally. 5. Temperature As temperature increases, the molecules, according to the 'Kinetic Theory' move faster, due to increased energy. Therefore, the enzyme and substrate molecules will meet more often and the rate at which the product is formed will increase. However, as the temperature continues to rise the hydrogen and ionic bonds, which hold the enzyme in shape, break and the active site will no longer accommodate the substrate. The enzyme is then said to be denatured - this cannot be reversed. 6. pH Efficient functioning of an enzyme depends upon the shape of its active site. This shape is determined, in part, by 2006-01-17T16:29:23-05:00 http://75.150.148.189/free-essay/Investigation-into-the-factors-that-effect-rennin-6379.aspx Stem Cells: Could This Be The Cure For Cancer? Stem Cells: Could this be the technology to cure cancer? By: Ali Ridha Stem cells could be the greatest medical advance in history in the sense that most of our serious diseases can be cured. Stem cells have the potential to morph into other cell types in the body. Serving as a sort of repair system for the body, they can theoretically divide without limit to replenish other cells as long as the person is living. During mitosis, each new cell has the potential to either remain a stem cell or become another type of specialized cell, such as a muscle cell, or a red blood cell. (University of Utah, 2004; Viegas et al, 2003; Parson et al, 2004; Facts on File, 2004). There are three kinds of stem cells in the body: Totipotent stem cells, which have the ability to morph into any kind of cell in the body. These are found in embryos undergoing their early stages. Another type of stem cell is pluripotent stem cells which have the ability to morph into almost any kind of cell in the body. These are found in a blastocyst which is the result of the embryo after 7 days after fertilization (University of Utah, 2004). They are enriched with pluripotent stem cells, which are constantly morphing into other types of cells in order to become a fetus. The last type of stem cell is multipotent stem cells or adult stem cells. These are found in fetuses as well as full grown adults. These stem cells can transform into most kinds of specified cells in the body, but their choices are more limited (Viegas et al, 2003). So why are these stem cells so important and how do they help cure cancer? As of today, there is something called stem cell therapy which is used to treat diseases using stem cells (Munson et al 2002). The goal of stem cell therapy is to repair damaged tissue that cannot heal itself. This is accomplished by transplanting stem cells into the damaged area and directing them to grow into new healthy tissue (University of Utah, 2004). Some stem cell therapies used today are, adult stem cell transplants using bone marrow stem cells, peripheral blood stem cells and umbilical cord blood stem cells. Cell based therapy is just one way to cure cancer, not the only way. For example, let us take the treatment of leukemia, 2005-11-07T22:57:10-05:00 http://75.150.148.189/free-essay/Stem-Cells-Could-This-Be-The-Cure-For-Cancer-6276.aspx Proteinaceous Infectious Particles Over the years there have been many documented cases of diseases for which there appeared to be no cause. Only within the late 20th century has the reason for these illnesses been brought into the spotlight. The symptoms of these illnesses are usually the loss of coordination followed by dementia, but in some cases an inability to sleep develops into dementia. These symptoms are caused by damaged regions of the brain. This damage occurs in the form of normal tissue changing to a sponge-like consistency. This is caused by cells clumping together and dying, leaving holes in the brain. These diseases fall into the category of spongiform encephalopathies (Collinge, 1995). This type of disease can occur in all mammals and is named after the mammal in which it is found. For example, in cows it is called bovine spongiform encephalopathy, or more commonly known as “mad cow disease”. Spongiform encephalopathies may also occur in humans in the form of Creutzfeldt-Jakob disease or Kuru, the latter of which was only found in the Fore tribe of Papua, New Guinea, members of which ate the brains of the dead as a sign of respect. Cannibalism was ended in 1958 due to health concerns. After the deaths of the 2600 afflicted persons, not a single case of Kuru has been recorded. The cause of spongiform encephalopathy is a small protein called a prion, or “proteinaceous infectious particle”. The protein was discovered and named in 1982 by Dr. Stanley B. Prusiner of the Department of Neurology at the University of California School of Medicine. At first, the discovery endured a great deal of skepticism due to the long accepted theory that only microbes can cause disease, which was proposed by Louis Pasteur. The prion protein (PrP for short) was first imagined when the agent that causes scrapie (the type of spongiform encephalopathy which occurs in sheep) was thought to lack nucleic acid (Alper, 1972). This was determined by subjecting infected tissue to ultraviolet or ionizing radiation, both of which are known to degrade nucleic acid. Afterwards, the tissue was injected into the brain tissue of a healthy subject. The infectivity of the tissue remained the same. This proved that there was no nucleic acid present in the infective agent, due to the fact that if it had been a viral or bacterial infection, the nucleic acid within the virus or bacteria would have been destroyed 2005-09-21T01:21:26-04:00 http://75.150.148.189/free-essay/Proteinaceous-Infectious-Particles-6237.aspx How Your Immune System Works How the Immune System Works The immune system defends the body from attack by "invaders" recognized as foreign. It is an extraordinarily complex system that relies on an elaborate and dynamic communications network that exists among the many different kinds of immune system cells that patrol the body. At the "heart" of the system is the ability to recognize and respond to substances called antigens whether they are infectious agents or part of the body, which are called self anitgens. T and B Cells Most immune system cells are white blood cells, of which there are many types. Lymphocytes are one type of white blood cell, and two major classes of lymphocytes are T cells and B cells. T cells are critical immune system cells that help to destroy infected cells and coordinate the overall immune response. The T cell has a molecule on its surface called the T-cell receptor. This receptor interacts with molecules called MHC or major histocompatibility complex. MHC molecules are on the surfaces of most other cells of the body and help T cells recognize antigen fragments. B cells are best known for making antibodies. An antibody binds to an antigen and marks the antigen for destruction by other immune system cells. Other types of white blood cells include macrophages and neutrophils. Macrophages and Neutrophils Macrophages and neutrophils circulate in the blood and survey the body for foreign substances. When they find foreign antigens, such as bacteria, they "engulf" and destroy them. Macrophages and neutrophils destroy foreign antigens by making toxic molecules such as reactive oxygen intermediate molecules. If production of these toxic molecules continues unchecked, not only are the foreign antigens destroyed, but tissues surrounding the macrophages and neutrophils are also destroyed. For example, in individuals with the autoimmune disease called Wegener's granulomatosis, overactive macrophages and neutrophils that invade blood vessels produce many toxic molecules and contribute to damage of the blood vessels. In rheumatoid arthritis, reactive oxygen intermediate molecules and other toxic molecules are made by overproductive macrophages and neutrophils invading the joints. The toxic molecules contribute to inflammation, which is observed as warmth and swelling, and participate in damage to the joint. MHC and Co-Stimulatory Molecules MHC molecules are found on all cell surfaces and are an active part of the body's defense team. For example, when a virus infects a cell, a MHC molecule binds to a piece of a virus or antigen, and displays 2005-05-12T05:16:45-04:00 http://75.150.148.189/free-essay/How-Your-Immune-System-Works-6157.aspx Breeding Roses (this comes in handy for biology if your studying plants and need some extra credit) Every rose breeder has certain more or less definite ideals or objectives toward which his breeding efforts are directed. Some of these ideals are shared by all rosarians, while others express the individuality of the breeder and may or may not find popular acceptance. Thus in my opinion an ideal red rose, for example, should have the following characteristics: 1. ) Vigor similar to Radiance 2 .) Long pointed or urn-shaped buds such as Lulu, Eclipse, or Charlotte Armstrong. 3 .) Glossy or semi-glossy, hard, leathery foliage. 4 .) High degree of mildew and rust resistance. 5 .) Everblooming, rapid "breaking habit". 6 .) Long cutting stems. 7 .) Strong neck. 8 .) Fragrance. 9 .) Absence of blue fading reaction. World's Fair is ideal in this respect. 10.) A high-centered open flower with 25 to 35 large petals. Breeding Plan Although the rose which perfectly meets these ideals may never be developed, any variety which is a step toward perfection is worthy of introduction. In my own experience most rapid progress toward combining all the above characteristics in one plant may be made by crossing variety A, having such desirable characteristics as mildew resistance and large glossy leaves, with variety B, having double dark red flowers but dull foliage, susceptibility to mildew, and short buds (unfortunately characteristics of most red roses so far introduced). Simultaneously variety A is crossed with variety C, having long buds, vigorous growth, and deep pink or light red flowers (hence carrying factors for red). Hybrids from cross A x B having wide glossy leaves, a high degree of mildew resistance, and deep pink or light red double flowers are then crossed with pink-flowered hybrids of A x C having the longest buds and most vigor. Large progenies must be grown in order to get the best combination of characteristics in a very few plants. These sister seedlings with wide glossy leaves, mildew resistance, and fairly long buds, are then crossed together, and in the resulting generation deep red roses having a vigorous growth habit, a high degree of mildew resistance, large glossy leaves, very long buds, and sufficiently double flowers may be expected. In order to understand the need for this type of breeding procedure, a discussion of rose chromosome numbers and behavior as they affect the inheritance of important characteristics is necessary. Mechanics of Inheritance Biologists are agreed that the factors determining the characteristics of plants and animals are serially located in certain deeply staining bodies of the cell 2005-05-12T05:15:43-04:00 http://75.150.148.189/free-essay/Breeding-Roses-this-comes-in-handy-for-biology-if-your-studying-plants-and-need-some-extra-credit-6156.aspx vaccines Since the first vaccine in 1796 for smallpox, made by Edward Jenner, modern science has managed to create vaccines to give us immunity to many deadly diseases. Vaccines have reduced many diseases and have even eradicated others. However, currently there is evidence that not all vaccines are beneficial and that some may actually be harmful. In this essay, I will discuss about what a vaccine is and how they work. I will also discuss the pros and cons of vaccinations, and show some of the advantages and disadvantages of a vaccine as well as the moral and ethical implications on our community. The word vaccine came from the word “vaca” which means cow in Latin. A vaccine is a means of producing immunity against pathogens, such as viruses and bacteria, by the introduction of weakened, killed, or altered antigens. In other words, it prepares the bodies defences against a particular pathogen before it strikes. There are a multiple amount of steps that the human body goes through in order to fight off the disease. First the vaccine is given by a shot or sometimes even in a liquid form by ingesting it. The antigens in the vaccine stimulate the body to produce antibodies, which neutralizes the antigen by binding specifically to it. These antibodies can fight the real disease germs, which can be roaming all around if they invade a human’s body. The antibodies will know how to destroy them and you will not become ill. This is called de-immunization. After exposure to a live, weakened, or dead germ, the antibodies or memory cells fight infectious diseases and usually stay in a person's immune system for a lifetime. There are many types of vaccines that have been generated throughout history. From Edward Jenner, who came up with a vaccination for small pox in 1796, to Louise Pasteur who developed vaccines for rabies and anthrax in 1885, all the way to present date with the research on a HIV/AIDS vaccine. One of the most successful vaccines that have ever been conjured up is the vaccine for Poliomyelitis, commonly known as the poliovirus or polio. Polio is a highly contagious, and sometimes fatal viral infection that can produce permanent muscle weakness, paralysis, and other symptoms. The polio vaccine is included among the routine childhood immunization. The vaccine can be taken orally (Sabin vaccine) or by an inactivated injection (Salk vaccine). In the early 2005-05-03T04:16:54-04:00 http://75.150.148.189/free-essay/vaccines-6129.aspx Natrual Selection Informitive Natural Selection Table of Contents Intro – Page 3 Natural Selection and Charles Darwin – Page 4-5 Herbert Spencer, Social Darwinism – Page 5 Arguments against Natural Selection - Page 6 Conclusion – Page 7 Bibliography – Page 8 Evolution is one of the most controversial topics that has been argued about for centuries. Natural selection is one of the main supports for the evolution theory; it is defined as: “the process in nature by which, according to Darwin's theory of evolution, only the organisms best adapted to their environment tend to survive and transmit their genetic characteristics in increasing numbers to succeeding generations while those less adapted tend to be eliminated”(4). A similar term would be “survival of the fittest.” For centuries Evolutionists have argued between themselves about the evolution of the human race. There are many different theories of natural selection, the first of which was proposed by Charles Darwin. Some of the common theories within natural selection include discussion of Charles Darwin, Herbert Spencer and Social Darwinism. When discussing evolution, one must also look at the common debates of natural selection because of its controversy. Natural selection occurs when a certain cell mutates in a favorable way to either help it survive or make it more likely to procreate. This is one of the bases for Darwinism in that, without that adaptation to the environment, a species would just die off at the first change in weather patterns or from being extinguished by predators. While sailing on the H.S.S. Beagle, Darwin wrote about this topic and other observations in his book: “On the Origin of Species.” One such observation was made about the population of different animals in relationship to each other: “From experiments which I have tried, I have found that the visits of bees, if not indispensable, are at least highly beneficial to the fertilization of our clovers; but humble bees alone visit the common red clover (Trifolium pratense), as other bees cannot reach the nectar. Hence I have very little doubt, that if the whole genus of humble bees became extinct or very rare in England, the heartsease and red clover would become very rare, or wholly disappear. The number of humble-bees in any district depends in a great degree on the number of field-mice, which destroy their combs and nests; and Mr. H. Newman, who has long attended to the habits of humble-bees, believes 2005-05-03T00:20:44-04:00 http://75.150.148.189/free-essay/Natrual-Selection-Informitive-6128.aspx Downs Syndrome Downs Syndrome- A Chromosome Abnormality Aimee-Kate 2005-01-31T22:17:49-05:00 http://75.150.148.189/free-essay/Downs-Syndrome-6019.aspx ABNORMAL CLINICAL CONDITIONS Dated: 14th January 2005:Time: 3:14 P.M. I have investigated numerous methods of study of biochemical techniques on Abnormal Clinical Conditions of patients.The procedures 2005-01-14T09:46:48-05:00 http://75.150.148.189/free-essay/ABNORMAL-CLINICAL-CONDITIONS-5991.aspx Establishing the role of sodium chloride in amylase 2004-11-20T05:01:34-05:00 http://75.150.148.189/free-essay/Establishing-the-role-of-sodium-chloride-in-amylase-5902.aspx Genetic Disorder: Tay-Sachs Disease My name is Put your name.. and I am a carrier of Tay-Sachs Disease; my partner is also a carrier of this disease and our child is affected with Tay-Sachs Disease. Tay-Sachs Disease is a recessive genetic disorder which contains harmful quantities of fatty substances called Ganglioside GM2 which harms the nerve cells in the brain. This disease mostly affect infants. The only way for a baby to be affected with this disease is when both of the parents is a carrier of this disease. There is a good 25% chance that the child with have this disease. An affected baby appears normal at birth and the first couple of months, but when the child is six months old, it begins to get the symptoms and they will even get noticeable cherry-red spots in the back of their eyes. When my child was six months old, I began to notice that he didn’t really move a whole lot, and that he had cherry-red spots on the back of his eyes. So I took him to the doctors and they told me that he has the disease called Tay-Sachs Disease. At first, I did not know what Tay-Sachs disease was until he told me a little bit about it and gave me a brochure on it. But, the part that upset me the most about this disease is that my partner and I were carriers of this disease and we gave it to him. After I learned more about this disease, I learned that there is no cure or treatment for this disease. The only thing that we could do was to make him as comfortable as possible. When he was about 2 years old he started to go blind, deaf, unable to grasp objects, he was unaware of his surroundings, he stopped smiling, couldn’t swallow and he became paralyzed. He got so bad that we could not take care of him anymore. We had to take him to National Tay-Sachs and Allied Diseases Association in Massachusetts. That was the only organization that would even take him. I felted so bad taking him there; I felt like a horrible parent that could even take care of her own child; having other people taking care of my child for me. Everyday, I would go down to that place and watch my child sit in a wheelchair and stare out the window, not moving, 2004-05-07T20:56:47-04:00 http://75.150.148.189/free-essay/Genetic-Disorder-Tay-Sachs-Disease-5620.aspx Germ Warfare Biological or germ weapons are living organisms used for the military and intended to cause diseases or death in human, animal, or plant life. They are made up of organisms that are highly contagious and reproduce very quickly. The groups using germs as their weapons depend on their fast reproduction. There are a wide range of techniques and agents that can be used in germ warfare. The most common 2002-11-08T13:00:00-05:00 http://75.150.148.189/free-essay/Germ-Warfare-5131.aspx Vitamin C Vitamin C is a water-soluble vitamin, and is also know n as Ascorbic Acid. It was first isolated in 1928 by the Hungarian biochemist and Nobel prize winner, Dr. Szent-Gyorgyi. Two-time Nobel prize winner, Dr. Linus Pauling was the first to realize vitamin C’s importance in a healthy immune system. Most animals can produce their own vitamin C. Man, primates (apes, chimps, etc.), and guinea pigs, however, have lost the ability. They instead have to get it through their diet. It was a Scottish physician named James Lind, back in 1753, who first said that fresh vegetables and ripe fruit could be used to prevent scurvy (a severe vitamin C deficiency, which is rarely seen today). The British Navy took his advice about 404 years later, taking lime juice on long sea voyages to ward off the disease. For this, they were nicknamed, “Limeys.” 42.2% of vitamin C comes from vegetables, 41.5% from fruits, 3.2% from dairy products, 2.3% from meat, poultry and fish, and .9% from other foods – legumes, nuts and soy (.1%) and miscellaneous foods (.8%). In the average American diet, 93% of their vitamin C comes from fruits and vegetables and citrus fruits and tomatoes contribute to almost half of the vitamin C provided by the fruits and vegetable group. Foods that contain small amounts of vitamin C and are not considered good sources of calcium can contribute a good amount of vitamin C to a diet if eaten often or in large amounts. Some good sources of vitamin C include broccoli, red peppers, parsley, potatoes, strawberries, and oranges, etc. Vitamin C can be damaged during food preparation, like when chopping, cooking, boiling, exposure to air, and being submerged in water. The amount of vitamin C is high enough in most foods though, that the amount after this is more than enough. To keep the vitamin C from being damaged you can eat fruits and vegetables raw whenever possible, and cook potatoes in their skin. Steam, boil or simmer in a small amount of water, or microwave for a short time. Refrigerate prepared juices and don’t store them longer than two or three days, and when storing cut/raw fruits and vegetables keep in an airtight container and refrigerate (don’t soak or store in water). The recommended dietary allowance (RDA) for adolescents is 75mg per day for males and 65mgs per day for females. Adults should have 90mg per day for 2002-10-01T14:00:00-04:00 http://75.150.148.189/free-essay/Vitamin-C-5023.aspx Presymptomatic Testing For Huntington Disease Huntington Disease, (HD), is a hereditary degenarative brain disease. Usually begining in mid-life, cells in the caudate nucleus of the brain begin to die, causing a relentless deterioration of intellectual ability, emotional control, motor skills, balance and speech. Chorea, or involuntary movements, is nearly always a symptom as well. HD is caused by a single dominant gene. Every child of an affected parent has a 50% chance of inheriting the gene that causes HD. The HD gene is found on chromosome 4. It is inherited as an autosomal dominant condition. Since it is not carried on one of the sex chromosomes, male and female offspring have the same chance of being affected. Presymptomatic testing is a method for identifying persons carrying the HD gene before symptoms appear. This can be useful for couples who have a history of HD in their families and wish to know if they have the HD gene before deciding upon having children. The genetic testing itself involves donating a small sample of blood that is screened in the laboratory for the presence or abscence of the HD mutation. Testing may require a sample of D.N.A from a closely related affected relative, preferably a parent, for the purpose of confirming the diagnosis of HD in the family. Genetic techniques used to do presymptomatic testing for the HD gene can be Gel Electrophoresis or Polymerase Chain Reaction (P.C.R). The Polymerase Chain Reaction is a technique used to amplify a particular fragment or sequence of DNA. Gel Electrophoresis is used to 'sort out' specific genes on D.N.A. Restriction enzymes are used to 'cut' the D.N.A sequence needed in P.C.R. P.C.R is a technique which is used to amplify the number of copies of a specific reigon of D.N.A to be adequately tested. The first step of P.C.R - Unknown D.N.A is heated, which causes the paired strands to seperate (single strands now accessible to primers). Second step - Add large excess of primers relative to the amount of D.N.A being amplified, and cool the reaction mixture to allow double strands to form again. Third step - To a mixture of all 4 individual letters (deoxyribonucleotides), add an enzyme which can 'read' the opposing strands 'sentence' and extend the primers 'sentence' by 'hooking' letters together in the order in which they can pair across from one another - A:T and C:G. The enzyme used in P.C.R is Taq Polymerase because it can withstand high 2002-08-28T14:00:00-04:00 http://75.150.148.189/free-essay/Presymptomatic-Testing-For-Huntington-Disease-4963.aspx What are the consequences from human activity that cause algal blooms? Streams, rivers, lakes, and wetlands contain a large part of our precious fresh water. Unfortunately they also act like drains, and everything we leave lying around ends up in them – acids, mercury, cadmium, and lead from industry and other resources; soil from logging operations; phosphorus and nitrogen from detergents; sewage, petrol, oil, plastic bags, aluminum cans and paper from roads and parks – the list is never ending. More often than not, the results are catastrophic. Being thoroughly discussed will be information about the death of rivers due to algal blooms e.g. Murray River, consequences the irrigation and agriculture organizations are causing, what is being done to prevent these problems and what the communities can do to help. “In 1991, a 1000-km-long stretch of the Darling River in New South Wales was entirely covered in poisonous blue-green algae…”(The State Of The Planet, John Nicholson, Pg.22), it was the largest toxic ‘algal bloom’ the world has ever seen. It happened because of two human activities. Algal blooms thrive on phosphorus and nitrogen – two important ingredients of farm fertilizers, animal and human waste, and detergents. Every year 440 tones of phosphorus and 1890 tones of nitrogen end up in the Darling River, mainly from farms and sewage treatment plants. Most rivers around the world have so much nitrogen in them they are unsafe for humans to drink. The algal blooms then use up all the oxygen in the water, so the fish suffocate and some water plants die. The poisonous algae also kill animals that drink at the river. This process only happens if the water is not moving. People pumping water out for irrigation, or holding it back in hydroelectric dams or town water storages and farm dams have reduced the flow of water in most rivers. The Goulburn River has 870 different engineering works along it, each of them helping to reduce the flow. The Upper Murray has 44. Many of the world’s major rivers have so much water taken out of them that they no long reach the sea, at least during the drier months. Another three examples of these situations are The Colorado (USA), Huang He (China), and the Murray (Australia). This is very bad news for many ocean fish, as they need to travel up the rivers every year to spawn in fresh water. And the problem doesn't stop there. Large areas of costal waters, 2002-05-04T14:00:00-04:00 http://75.150.148.189/free-essay/What-are-the-consequences-from-human-activity-that-cause-algal-blooms-4724.aspx Acne - Skin's Miniture Volcanoes This purpose of this paper is to explain the cause of acne, give some examples, and how to get help prevent it. This paper will also dispel some of the myths of acne and how it is caused. Acne is a condition of the skin that ranges in appearance from raised bumps to pustules (large cysts and pimples). Acne is so common that more than 80 percent of the population will have some form of it at some time in some time of their lives. Although there are several theories about what causes acne, authorities generally believe that acne is a by-product of hormonal changes in the body during puberty- that period of life when a child develops the secondary sex characteristics (such as facial and body hair, deepened voice, and increased muscle mass in boys and breast development and breast development and menstruation in girls). At this time, production of hormones (particularly the male hormone testosterone) increases and stimulates sebaceous glands in the skin to produce sebum (an oily secretion). Most excess oil produced by these glands leaves the skin through the hair follicles (the tube like structures from which the hair develops). Sometimes, oil clogs these tubes and creates comedones (blocked hair follicles). Comedones are what form the initial lumps in acne. If comedones are open to the surface of the skin, they are called blackheads. They contain sebum from the sebaceous glands, bacteria, and any skin tissue that accumulates near the surface. Comedones that are closed at the surface are called whiteheads. Plugged follicles can rupture internally, resulting in a discharge of their contents into the surrounding tissues. This process begins an inflammatory response that sets the stage fore the development of acne. The role of the bacteria is acne is unclear. Bacteria may act by causing chemical reactions in the sebaceous fluid, leading to the release of very irritating compounds called fatty acids. These in turn may cause inflammation that increases susceptibility to infection. Authorities disagree about the role of diet as the cause of acne. Diet alone does not cure acne, nor does stem from an allergic reaction to a specific food. However, some cases of acne appear to improve after eliminating certain foods, particularly chocolates and fats. In addition, emotional stress seems to increase the severity of acne in certain cases. Acne causes raised swellings, most frequently on the face, neck, and back, chest and shoulders. In severe cases, 2002-05-03T14:00:00-04:00 http://75.150.148.189/free-essay/Acne-Skin-s-Miniture-Volcanoes-4722.aspx The Biology and Operation of a Septic System <H2>Introduction to Septic Systems</H2> The septic system is a grouping of components working together to decompose household waste water. The septic tank holds the waste and breaks the organic compounds into a solid, liquid or gas. The solid waste (called sludge) settles to the bottom of the tank and must periodically be removed. The liquid waste is flushed to the distribution box and is then allowed to drain into the ground through a series of perforated pipes (often called lines or a leach field). Gases follow the same path as liquids and eventually rise through the soil and enter the atmosphere. Tanks can be arranged in series for additional waste treatment. Many older systems have no distribution mechanism. <H2>The Septic Tank Layers or Horizons</H2> Wastewater flows through a pipe into the septic tank. Baffles or "tees" at the inlet and outlet of the tank slows the flow of water and prevents sewage from flowing directly through the tank. Bacterial action within a septic tank helps to break down the solids in the wastewater. The tank must be large enough, and the rate of flow small enough, to ensure sufficient "residence time" of wastewater within the tank. The solids which cannot be broken down sink to the bottom of the tank and accumulate as sludge. Grease, foam, and lighter particles float to the surface and form a layer of scum. The exit baffle holds back sludge and scum while allowing a partially digested wastewater to flow out of the tank. This picture depicts the three layers within the septic tank. Anything that floats rises to the top and forms a layer known as the scum layer. Anything heavier than water sinks to form the sludge layer. In the middle is a fairly clear water layer. This body of water contains bacteria and chemicals like nitrogen and phosphorous that act as fertilizers, but it is largely free of solids. <H2>Organic Substances</H2> <li>The concentration of natural and synthetic compounds in effluent are generally expressed in terms of: <li>Biological Oxygen Demand (BOD), the measure of how much oxygen is required to finish digesting the organic material left in the effluent. <li>Chemical Oxygen Demand (COD), the measure of how much oxygen is required to finish the decomposion of chemicals. <li>Total Suspended Solid Content (TST) <li>Total phosphorus and nitrogen - measures the nutrients remaining in the water A properly designed and maintained septic tank removes most of the organic substances from raw wastewater. Additional removal 2002-02-09T13:00:00-05:00 http://75.150.148.189/free-essay/The-Biology-and-Operation-of-a-Septic-System-4356.aspx Pharmacology The word pharmacology comes from the Greek word for drug, pharmakon. Pharmacology deals with the actions of drugs on the body, development and testing of new drugs, and new uses of existing drugs. It uses the knowledge of chemical properties and biological effects to determine the uses and reactions of the drugs. Although many drugs are made from plants and animals, pharmacologists try to create synthetic versions based on their chemical structure. Pharmacology combines many sciences together including biology and chemistry. A Bachelor of Science in pharmacology is needed to do technical jobs while a pharmacologist with a Master's Degree can work as a technologist or do independent research. A pharmamcologist's salary is determined by their education. With a Master's degree they can earn, on average, between $30, 000 and $40,000. With a Ph.D. they can earn, on average, between $35,000 and $55,000. An experienced researcher can earn over $60,000. A drug is a chemical that effects living organisms whether through medicinal purposes (acetylsalicylic acid), everyday substances (caffeine), or illegal substances (marijuana). The active ingredients are usually mixed with nonactive ingredients to make it easier to take in. Acetylsalicylic acid, also known as aspirin, is an everyday drug used to relieve pain. The molecular formula is C9H8O4. The molecular weight is 180.16 newtons. Because we know what the molecular formula is, we can determine what will react and what won't inside the body. Aspirin is incompatible with strong oxidizing agents, strong bases, strong acids, various other compounds such as iodides, iron salts, quinine salts, etc. With knowledge of this, it makes the job of determining new and safer uses of drugs easier to find. To help pharmacologists develop drugs they need the assistance of computers to help them determine the molecular modeling of the drugs. The action of the drug is related to it's chemical structure and small changes in the structure can affect the drug's action. Many synthetic drugs have been produced after determining it 's chemical structure. Synthetic drugs are useful because it's gives the researchers a way to find ways of making a drug with less side effects, including acetaminophen and ibuprofen. Pharmacology deals with many other sciences and is a very demanding job. There is always room for improvement but a pharmacologist's work is never complete. There is always another cure or treatment for a disease or virus to be found. Pharmacologists must use their knowledge of chemistry 2002-01-16T13:00:00-05:00 http://75.150.148.189/free-essay/Pharmacology-4281.aspx Down syndrome and Spina Bifida - cause, effects and treatment Many individuals are born with defects due to genetic factors. Some such defects occur because the child inherits a defective gene, or genes from the parents. Others are caused through mutations- spontaneous changes that occur to a gene or chromosome. Environmental factors affecting the foetus during the uterine development may also cause defects. If, during pregnancy, a woman smokes, consumes alcohol or other drugs, or suffers dietary deficiencies, the developing foetus may be adversely affected. About one in every seven hundred births is Down syndrome baby. Down syndrome is now more frequently referred to as trisomy- 21, as new individuals with the disorder have three of the chromosome numbers twenty-one. Characteristics of a baby with Downs Syndrome include a small, round head with a large tongue and a broad skull; a short stature and stubby fingers; malformation of the heart, ears, hands and feet; and mental retardation. Sexual maturity is rarely attained. The risk of having a child with Down syndrome increases sharply if a woman is reaching the end of her child-bearing period. For women aged over 45 or over the risk is around one in fifty, whereas for women in their middle reproductive years- around 20-35 years- the risk is only about one in a hundred. Down syndrome can be detected in cells taken from the amniotic fluid of a pregnant woman, in a procedure called amniocentesis. Women having children late in life are strongly advised to have such a test. If the condition is detected early in the pregnancy, the parents have the option of a therapeutic abortion, whereas such practices are legal. About two in every thousand babies born in Australia have a neural tube defect and about half of these have spina bifida. Spina bifida occurs when the vertebrae of the spinal column fail to form a complete bony arch around the spinal cord. In about fifty percent of cases it is the lower back region of the spine that is affected. In serious cases, the coverings of the spinal cord and the wall of the spinal cavity itself may protrude, resulting in the opening of the neural canal to the exterior. Surgery to repair this is condition often results in paralysis of the lower limbs and associated lack of control of bowel and bladder functions. In less severe cases the spinal deformity may be small, and when it is repaired the child is able to walk and 2001-12-10T13:00:00-05:00 http://75.150.148.189/free-essay/Down-syndrome-and-Spina-Bifida-cause,-effects-and-treatment-4139.aspx Anemia Anemia is a disease of the blood. Anemia is characterized by a deficiency in red blood cells or in the concentration of hemoglobin in the body. These deficiencies are caused by either decreased production or increased destruction of blood cells. Anemia is most common among women in their reproductive years, infants, and the elderly. Because one of the major functions of red blood cells is to transport oxygen, a decrease in red blood cells decreases the amount of oxygen delivered to the body's tissues, which results in the symptoms of anemia. Iron deficiency anemia is the most common form of anemia. Approximately 20% of women, 50% of pregnant women, and 3% of men are iron deficient. Iron is an essential component of hemoglobin. Iron is normally obtained through the food in the diet and by the recycling of iron from old red blood cells. High-risk groups include: women of child-bearing age who have blood loss through menstruation; pregnant or lactating women who have an increased requirement for iron; infants, children, and adolescents in rapid growth phases; and people with a poor dietary intake of iron through a diet of little or no meat or eggs for several years. Folate or folic acid is necessary for red blood cell formation and growth. Dietary sources of folate are found in green leafy vegetables and liver. Because folate is not stored in the body in large amounts, a continual dietary supply of this vitamin is needed. In folate deficiency anemia, the red cells are abnormally large and are referred to as megalocytes, and in the bone marrow as megaloblasts. Subsequently, this anemia may be referred to as megaloblastic anemia. Causes of the anemia are poor dietary intake of folic acid as in chronic alcoholism, malabsorption diseases such as celiac disease and sprue, and certain medications. Deficiencies due to increased need for folic acid may occur in the third trimester of pregnancy. Risk factors are a poor diet, overcooking food, alcoholism, having a history of malabsorption diseases, and pregnancy. Vitamin B12 is essential for normal nervous system function and normal red cell, white cell and platelet production. All sources of vitamin B12 come from the diet in animal products, including dairy and eggs. Causes of vitamin B12 deficiency include a strict vegetarian diet excluding all meat, fish, dairy products, and eggs and chronic alcoholism. Anemia of B12 deficiency that is caused by a poor diet can be prevented 2001-11-11T13:00:00-05:00 http://75.150.148.189/free-essay/Anemia-4031.aspx Skin Cancer: Melanoma <b>What causes melanoma?</b> Scientists do not yet know exactly what causes melanoma skin cancer, but we do know that certain risk factors are linked to the disease. Some risk factors, like smoking, can be controlled. Others, like a person's age or family history, can't be changed. But having a risk factor, or even several, doesn’t mean that a person will get the disease. <b>Risk Factors for Melanoma Skin Cancer</b> <li>Moles: Moles are (not cancerous) skin tumors. People with lots of moles, and those who have some large moles, have an increased risk for melanoma. <li>Fair skin: Fair skin, freckling, and light hair increases the risk of melanoma. <li>Family history: Around 10% of people with melanoma have a close relative (mother father, brother, sister, child) with the disease. <li>Immune weakness: People who have been treated with medicines that suppress the immune system have an increased risk of developing melanoma. <li>UV radiation: Too much exposure to UV radiation is a risk factor for melanoma. The main source of such radiation is sunlight. <li>Age: About half of melanomas occur in people over the age of 50. But younger people can get melanoma too. <b>What Is Melanoma?</b> You've heard the term "melanoma" before, but what does it mean? Let me help you understand. Cancer occurs when cells in a part of the body begin to grow out of control. Although there are many kinds of cancer, they all come about because of rapid growth of abnormal cells. Different kinds of cancer can behave very differently. For example, lung cancer and breast cancer are very different diseases. They grow at different rates and respond to different treatments. That's why people with cancer need treatment that is aimed at their kind of cancer. Because they behave differently, skin cancers are divided into two major groups: melanoma skin cancer and nonmelanoma skin cancer. This research report covers melanoma skin cancer only. Melanoma begins in the cells (melanocytes) that produce the skin coloring. In order to understand melanoma, it's helpful to learn about normal skin. <b>Normal Skin</b> The skin is the largest organ in the body. It covers and protects the organs inside the body. It also protects the body against germs and prevents the loss of too much water and other fluids. The skin sends messages to the brain about heat, cold, touch, and pain. The skin has three layers. From the outside in, they are: the epidermis, the dermis, and 2001-11-04T13:00:00-05:00 http://75.150.148.189/free-essay/Skin-Cancer-Melanoma-3976.aspx Sickle-Cell Anemia Sickle-Cell Anemia is an inherited blood disorder that affects millions of people around the world. It is particularly common among people whose ancestors come from sub-Sahara Africa and Spanish speaking regions. Approximately 2 million Americans carry the sickle cell trait. Sickle-Cell Anemia is caused by an error in the gene that tells the body how to make hemoglobin. The defective gene tells the body to make the abnormal hemoglobin that results in deformed red blood cells. The presence of two sickle-cell genes is necessary for a child to have the disease. Which means there is about a 25% chance for a child to have the 2001-10-20T14:00:00-04:00 http://75.150.148.189/free-essay/Sickle-Cell-Anemia-3878.aspx Skin Cancer <center><b>What Keeps Us Alive Can Also Kill Us</b></center> Skin cancer is the most common type of cancer in the United States. According to current estimates, 40 to 50 percent of Americans who live to age 65 will have skin cancer at least once. There are two different types of skin cancer: Melanomous and non-melanomous. To understand both of these terms a little better you need to be aware that your skin is divided up into 3 layers: the epidermis, dermis, and subcutis. The top layer, the epidermis, is very thin and serves to protect the deeper layers of the skin. The epidermis is also composed of basal cells, which in turn divide to form squamous cells and melanocytes. Melanoma skin cancer develops from the melanocytes and non-melanomous skin cancer develops from the basal and squamous cells. There are 2 types of non-melanomous cancer that result from these cells. The first is basal cell carcinoma, basal cell carcinoma begins in the lowest layer of the epidermis, the basal cell layer. About 75% of all skin cancers are basal cell carcinomas. This type of skin cancer tends to be slow growing and is usually found in areas that are highly exposed to sunlight, such as the head or neck. The second type is called squamous cell carcinoma. Squamous cell carcinoma accounts for 20% of all skin cancers, and penetrates the skin more than basal cell would, therefore, is considered to be more harmful. Unlike non-melanomous skin cancer, melanomous is much more uncommon and much more deadly. Melanomous skin cancer accounts for less than 4% of skin cancer cases, but causes about 79% of skin cancer deaths. The American Cancer Society predicts that in the year 2000 about 7,700 people will die of this cancer. Surprisingly, even with these astonishing numbers people still continue to put themselves at risk everyday. Through the efforts of organizations such as the American Cancer Society people are becoming more aware everyday of the severity of skin cancer. The solution to all this is very simple, we all need to wear sunscreen (at least SPF 15) when planning to expose ourselves to the sun. There are also other everyday preventive measures that we can take to decrease our chances of harmful exposure to the sun. It is always helpful to wear a shirt and a hat with a broad brim. Wear sunglasses that absorb 99%-100% of the UV rays to help 2001-10-20T14:00:00-04:00 http://75.150.148.189/free-essay/Skin-Cancer-3879.aspx Retinoblastoma Victims of retinoblastoma are infants and toddlers under the age of five years old. Many victim's symptoms indicate they have this cancer. Many symptoms are: that the pupil is observed to be wite, or, if the eye turns outward toward the ear. Children that have retinoblastoma may also have a red, painful eye, poor vision, inflammation of tissue surrounding the eye, an enlarged or dialated pupil, different colored irises. The number one cause of retinoblastoma is from heredity, but many researchers still have questions on how else the cancer comes to play without the heredity side. If a patient's parent is fully aware of the child's eye the pediatrician will then take the child in for a full eye examination. Some retinoblastoma patients may laso have extra fingers or toes, malformed ears, or even retardation. On rare occasions, retinoblastoma is discovered on a well-baby examination. Every year, one out of every fifteen to thirty thousand children are affected by retinoblastoma. Children are affected in either one eye (unilateral) or in both eyes (bilateral). In most cases (over 75%) the cancer is only involved in one eye; the rest are affeted in both eyes. Most retinoblastoma patients have no famly history of the disease; only 10% do have other family members with retinoblastoma. Approximately, only twenty-five to thirty people actually die from retinoblastoma in the United States annually. The prognosis of someone with retinoblastoma can greatly change depending on where the tumor is located and if it has spread to other parts of the body. The tumor is classified according to how dangerous it is. Usually the pediatrician can tell by how serious the tumor is by how far it has spread, if the tumor is still contained in the eye there are many treatments that the patient can choose form. But, if the disease has spread throughout hte body into the brain then the tumor(s) is treated with chemotherapy. Retinoblastoma can be treated with many options. The treatment depends upon the age of the child, the involvement of one or both eyes, and whether or not the cancer has spread to other parts of the body. No treatment may mean that the child would die. Most goals for treatment from most to least impport ranking are: saving the child's life, maintaining the eye and vision, and preserving cosmetic appearance. THe most common form of treatment for retinoblastoma is enucleation. During an enucleation the eye 2001-10-18T14:00:00-04:00 http://75.150.148.189/free-essay/Retinoblastoma-3867.aspx Genetic Modification of Foodstuffs Virtually every crop we eat have undergone hundreds of years of genetic modification by farmers and scientist in search of desirable traits. Selective breeding and hybrid strains have contributed immeasurably to farm productivity during this time. Over the past 30 years however, genetic engineering has been revolutionized. While before, a farmer wanting to develop a frost resistant tomato would be able to breed towards one only if the necessary genes were available somewhere in tomatoes or a near relative to tomatoes, modern biological engineering techniques overcome such restrictions. Genetic traits from outside a species’ gene pool, in the tomato’s case from an arctic fish, can be spliced into the organism to create an entirely different species, a transgenic organism with the typical traits of a tomato and frost resistance from a fish. The most widely used method of gene splicing, recombinant DNA, uses biochemical "scissors" called restriction enzymes to cut the strings of DNA, selecting required genes. These are then “ferried” by a virus or a bacterium that infects the host, smuggling the gene into the plant's DNA. In this way scientists have been able to create slow ripening and seedless fruit, crops that grow in unfavourable conditions and are resistant to disease or herbicides and milk from cows given a genetically engineered growth hormone. The benefits of gene technology in terms of food production are enormous. The most common genetically engineered crops contain modifications that make the plants resistant to certain diseases and herbicides, or allow them to produce their own pesticides, thereby eliminating or reducing the need to spray. So-called "Bt corn," for example, contains a gene resistant to the harmful mycotoxin fungus and herbicide producers, Monsanto have created a strain of soybeans genetically modified to be unaffected by their product Roundup. The soybean farmer therefore can avoid targeting specific weeds and require just one application of a general weed-killer, reducing costs and agricultural waste run-off. Genetically modified crops are also being adapted to grow in salty, dry or frosty environments, contain edible vaccines, have a longer shelf life and be more nutritious. A group of Swiss and German scientists recently developed a strain of GM rice know as ‘golden rice’ due to its altered colour. Containing genes that produce a unusually high amount of beta-carotene (vitamin A), this rice could be a solution to the thousands of poor children in Asia who eat little but rice and go blind or 2001-10-05T14:00:00-04:00 http://75.150.148.189/free-essay/Genetic-Modification-of-Foodstuffs-3804.aspx Evolution and Charles Darwin Charles Robert Darwin has had the greatest influence on the world by proving the evolution of living things. Charles Darwin had first noticed the similarities of plants and animals when he took a five-year cruise on the H.M.S. Beagle, which was available to him through a friend from school. During the cruise Charles Darwin started becoming interested with the similarities between the plants and animals that were similar on different islands with similar climates, so he decided to study them more closely. With the studies that Charles Darwin obtained he published his first work, “The Origin of Species.” In this book he explained how for millions of years animals, and plants have evolved to better help their existence. Darwin reasoned that these living things had gradually changed over time to help themselves. The changes that he found seemed to have been during the process of reproduction. The traits which would help them survive became a dominant trait, while the weaker traits became recessive. A good example of what Darwin was trying to explain is shown in giraffes. Long-necked giraffes could reach the food on the trees, while the short-necked giraffes couldn’t. Since long necks helped the giraffes eat, short-necked giraffes died off from hunger. Because of this long-necks became a dominant trait in giraffes. This is what Charles Darwin would later call natural selection. Charles Darwin also showed how new species were created on the acts of evolution. It is easily explained by having big differences from the effect of natural selection, which were considered to be new species. So back in the beginning, before the effects of evolution had occurred there was just one specie, which evolved to make the species that we know today. So somehow all species are somewhat connected. The basis of what Darwin was proving was that life on Earth is simply the result of billions of years of adaptation to the changing environments. That is why certain species can only live in certain climates. This can be explained with the color of your skin, or the growing of plants. The color of your skin used to depend on where you live. (Before transportation became so easy.) Darker skinned people would live where it is hotter, and the sun shines more. Lighter skinned people would live in cooler, less sunny areas. This is because the darker pigments in your skin would keep you from burning. (Like when you 2001-08-11T14:00:00-04:00 http://75.150.148.189/free-essay/Evolution-and-Charles-Darwin-3629.aspx The Latest Advances in Drug Manipulations of the Immune System <b>INTRODUCTION</b> In order to provide a detailed analysis of recent pharmacological developments involving the human immune system, it is firstly necessary to introduce the innate and adaptive immune responses . Immunosuppressants and immunomodulators will be differentiated between and a selection of new and often experimental drugs belonging to each category will be provided. Specific drugs will be described including the pharmacokinetics and pharmacodynamics involved with each type. The possible clinical uses will be alluded to along with details from recent research. <b>INNATE IMMUNITY</b> Innate immunity is the first line of defence and comprises physical (skin), biochemical (complement, lysozyme) and cellular (macrophages, neutrophils) mechanisms (Katzung, 1998). All these mechanisms are non-specific, anti-microbial agents which work in conjunction with adaptive immune responses to provide a more effective system (Downie et. al., 1995). <b>ADAPTIVE IMMUNITY</b> The adaptive immune system is split into two mechanisms: humoral immunity and cell-mediated immunity. A basic understanding of these concepts is necessary for the purpose of understanding the specific effects of different immunopharmacological agents. <b>HUMORAL IMMUNITY</b> Humoral or antibody-mediated immunity is associated with B-lymphocyte cells. Antigens are foreign molecules that initiate an immune response, they have inherent immunogenicity (Tortora & Grabowski, 1996). Upon contact with an antigen, B-cells divide to produce a clone of plasma cells capable of the production of antibodies. Antibodies are immunoglobulins, modified blood proteins with a specific action against antigens. Five main sub-types of immunoglobulins have been identified of which IgG is the most abundant in bodily fluids (Hopkins, 1995). Several cells are known to initiate the process of plasma cell differentiation and are known collectively as antigen presenting cells (APCs) (Waller & Renwick, 1994). <b>Lymphokines</b> The antigen on the surface of the APC triggers TH-cells to produce hormone-like lymphokines (Lessof, 1993). Lymphokines are cytokines, regulators of the immune reactions which are produced by lymphocytes. Examples of these chemicals include interleukins, interferon and tumour necrosis factors. Their action involves the regulation of the proliferation, differentiation and activity of leukocytes (Dale et. al., 1994). The nature of lymphocyte stimulation will determine which class of immunoglobulin will be produced (Waller & Renwick, 1994). <b>The role of complement & antibody-antigen complexes</b> Antibodies have two distinct functions: to recognise and combine with an antigen, and to activate a defence mechanism for example by activating the complement sequence (Dale et. al., 1994). This sequence involves more than thirty proteins (Mollnes & Harboe, 1996) and has the function of the destruction and removal of invading micro-organisms and subcellular debris and 2001-08-09T14:00:00-04:00 http://75.150.148.189/free-essay/The-Latest-Advances-in-Drug-Manipulations-of-the-Immune-System-3622.aspx Anorexia Nervosa Anorexia Nervosa is characterized by a refusal to maintain a minimal normal body weight. A disturbance in perception of body shape and weight is an essential feature of anorexia nervosa. It appears to be far more present in industrialized societies, in which there is an abundance amount of food and in which being considered attractive is linked to being thin. The disorder is most common in countries like the United States, Canada, Europe, Australia and Japan. More than 95% of cases of anorexia nervosa occur in females between the ages of 14 and 45 years. Most researchers agree that out of every 200 American girls between the ages of 12 and 18, one will develop anorexia to some degree. Therapists find that persons with anorexia usually lack self-esteem and feel they can gain admiration and attention by losing weight and becoming thin. There is no single cause of anorexia nervosa, because it’s a complex disorder with multiple causes that may be different for every person. From what is know it seems that this is a disorder of many causes that come together to produce the illness. These recognized causes include the nature of the personality of the girl herself, aspects of her family its members and relationships, and stresses and problems occurring outside the home, often at school. There is an increase risk in families in which there are other anorexics and this probably indicates a genetic cause also. Some theorists have pointed to socialcultural factors as potential causes for anorexia. Distorted body images and dissatisfaction on the part of anorexia patients may be influenced by how weight is portrayed in the media and our cultural values about women’s appearance. Anorexia Nervosa is a disorder of self-starvation that has both physical and psychological consequences. The first physical signs of anorexia nervosa include emaciation, constipation, dry skin and brittle nails. As the heart muscle deteriorates, the rhythm often changes putting the anorexic at risk of heart attacks. Malnutrition and starvation place the anorexia patient at risk for bone loss, infertility and osteoporosis. Starvation places the body under a great deal of stress, increasing the rates of kidney failure, heart failure, and respiratory infections. As the disorder progresses, the psychological consequences become evident. The previously hard-working, over-achieving perfectionist becomes less interested in activities that once brought her pleasure. She experiences difficulty concentrating, loses interest in school, and focuses more on intensive exercise and dieting. 2001-08-06T14:00:00-04:00 http://75.150.148.189/free-essay/Anorexia-Nervosa-3613.aspx Down Syndrome Sometimes when meiosis ( the division of reproductive cells ) occurs, chromosomes may be lost, left behind, or too many may be passed on, resulting in the birth of a child with a genetic or congenital defect or disease. One of the most common of these genetic disorders is Down syndrome. This disorder takes its name from Dr. Langdon Down, who was the first to describe it formally, in 1866. Down syndrome is a condition marked by abnormal physical and mental development that is caused by a genetic defect. This genetic defect is caused by an extra chromosome. People born with Down syndrome have 47 chromosomes compared to the normal amount of 46, 23 chromosomes inherited from each parent. This extra chromosome originates more often in the mother's egg than the father's sperm. Chromosomes are individual, large DNA molecules in a cell nucleus. They contain the genes along with structures that hold the DNA and aid it in expressing heredity by orchestrating cellular operations. Down syndrome is one of the most common chromosomal abnormalities, occurring in about 1 out of 800 births. However, the frequency of the disorder varies greatly according to the age of the mother. For women in their twenties the rate is 1 in 2,000 but it rises steeply to 1 in 100 by the time a woman reaches 40. Down syndrome is usually recognized soon after birth because of characteristic facial features such as a flattened nose, upward slanting of the eyes, a large tongue that often protrudes from a small mouth, a small, rounded head, and a short stature. Other symptoms that might only be noticed by doctors include congenital malformations of the heart of gastrointestinal system, flabby muscle tone and poor coordination due to poor control over the motor nerves, poorly functioning endocrine glands, narrow ear canals, low resistance to infection, weak vision, and misshapen teeth with thin enamel. All children with Down syndrome also have learning difficulties to some extent and there is a large variation in handicap. In some cases Down syndrome may be discovered before birth through a test known as amniocentesis in which fluid is taken from around the baby and the fetal cells are examined for the extra chromosome. People with Down syndrome are usually exceptionally happy, gentle, and loving. As children, they need loving care and extra attention to make sure that their minds are stimulated. Special teaching is 2001-05-13T14:00:00-04:00 http://75.150.148.189/free-essay/Down-Syndrome-3365.aspx Wetland Research Paper When most people think of wetlands the first thing that will pop into their mind will be visions of swamps and flooded plains. These marshy lands would seem to have no purpose, while in reality they are the most precious form of ecosystem that we have in America. Wetlands contribute to biodiversity, clean water, flood control, and provide a habitat for millions of species of plants and animals. Even with all this wetlands still face mass destruction, much like the rain forests they are just as productive and face similar rates of devastation (Mitchell, J. (1992, October). “Our Disappearing Wetlands” National Geographic, Pg 15). It really is hard to get someone passionate about a mosquito-infested piece of swamp that seems just to be there to take up space and look bad. This is why wetlands are not backed by too many people to prevent their destruction. The main causes of wetland devastation are all linked to man. Pollution, construction, and farming are what is destroying 300,000 acres of wetlands each year (David Allen, J 1995 Pg. 24). Pollution is one of the most potent forms of destruction in that a small amount can cause such damage to a wide variety to plants and wildlife. Construction is another threat because as the population grows the demand for affordable housing goes up. Also with a rise in population comes a demand for food, which leads the to last and most destructive threat to wetlands, farming. Farming is all the threats to wetlands rolled into one; it builds over hundreds of acres of land and pollutes it with fertilizers and herbicides. There are many misconceptions about wetlands that the public has due to the fact that there is not much public interest to save the wetlands. Well what exactly is a wetland? A lowland area, such as a marsh or swamp, that is saturated with moisture, especially when regarded as the natural habitat of wildlife, but in actuality a wetland is so much more than that. Depending on the type of wetland suggests the function it performs for the environment. We now realize that wetlands are important and valuable ecosystems. They are home to many beautiful and rare species. They filter runoff and adjacent surface waters to protect the quality of our lakes, bays and rivers. Wetlands also protect many of our sources of drinking water. They are the source of many commercially and 2001-05-09T14:00:00-04:00 http://75.150.148.189/free-essay/Wetland-Research-Paper-3342.aspx Ocean Deep Snelgrove and Grassle in The Deep Sea: Desert and Rainforest published in Oceanus, volume 38 in 1995 argue that the popular belief that the deep sea is little more than an “ocean desert” is a pure fallacy. Contrary to such thinking a multitude of benthic organisms dwell on the ocean bottom; despite the frigid temperatures and high pressure, a large heterogeneity of creatures, rivaling in variety and number those inhabiting tropical rainforests, thrive in this environment. The “analogy of the ocean desert” arose from the technologically inadvanced photographs and sampling equipment prior to the 1960’s (25). However, it was during that decade that WHOI biologists Sanders and Hessler, employing an epibenthic sled, produced extremely varied samples of organisms from deep-sea communities. The epibenthic sled permitted researchers to observe organisms that had previously gone unnoticed; unknown to the scientific community was a varied population of macrofaunal benthos inhabiting the bottom sediment, in addition to new species of polychaetes, crustaceans, and mollusks. Further sampling in the 1980’s, with the use of a box corer, revealed an astoundingly heterogeneous population of benthic organisms equal, or perhaps more expansive in variety than the number of species residing in the tropical rainforests. Therefore, though the deep-sea may physically resemble a desert with its “large expanses of . . . gently rolling contours of mud or sand with little visible life,” in reality it is an ecosystem teeming with life (27). Such diversity was most noteably evidenced by a sample taken from an area no larger than seven feet by seven feet off the coast of Charleston, South Carolina where a total of 1,597 divergent species were recovered from the ocean bottom in a single sampling. The heterogeneity among species is also apparent with respect to both “space and time” (28). Observations have revealed that different species dwell in different patches along the ocean bottom; this patchwork of species is what, in effect, provides all species in the deep-sea with adequate sustenance. Phytoplankton blooms, sinking fish carcasses, pieces of wood, pieces of seaweed, disturbances created by fish feeding, and the polychaete fecal mounds all create microhabitats within the larger habitat of the ocean bottom; different species derive sustenance from different patches or microhabitats generated by such activities. In addition, seasonal changes and the passage of time affect these microhabitats and thus, those organisms present in each. Therefore, it is the heterogeneity of the deep-sea habitat with its mosaic 2001-04-30T14:00:00-04:00 http://75.150.148.189/free-essay/Ocean-Deep-3282.aspx Biodiversity Biodiversity is described by Ruth Patrick as, “the presence of a large number of species of animals and plants…”(Patrick 15). In other words, biodiversity is the term for the measure of the variety of different species that do exist still on our plant. These species can range from the simplest bacteria to the very complex primates. Biodiversity can relate locally or globally. For example the Southern New England forest contains 20 or 30 tree species while in the rainforest of Peru there are hundreds of species of trees (Patrick 15). There are also further ways to view biodiversity and that is in levels. These levels can be the “diversity of higher plants, number of species, or expressed as sheer weight (biomass)” (Patrick 15). Biodiversity is different is each part of the world. Not every part of the world contains the same amount of creatures yet there are parts of the world that might contain similar amounts. These regions of the world have similar weather patterns and therefore similar species will develop there but they are not necessarily the same. One of the more important regions of the world that contain a large amount of biodiversity is the tropical rainforest region. “The forests comprise roughly 7% of the dry land surface of Earth and may hold more than 50% of all species” (Patrick 15). Yet us as humans do not know all of the creatures and organisms that live on this planet at all. We only have discovered, in one way or another, about 1.4 million species yet the number that is estimated is about 10-100 million (Patrick 15). The unknown species that do exist on this world can have many and countless benefits to the human race. A good example can be the rosy periwinkle, which is a plant found on the island of Madagascar, helped cure the Hodgkin’s disease and lymphocytic leukemia. (E.O. Wilson 3). Another can be the cyclosporin that was found in an obscure Norwegian fungus that is the foundation for the organ transplant business (Wilson 3). There also exist countless other potential uses and numerous other benefits that can be found in nature. The only problem is that we do not know even half of the amount of life that exists on this planet and many of them are disappearing faster than we can discover. With the advancement of technology and the growing population go mankind, nature 2001-04-30T14:00:00-04:00 http://75.150.148.189/free-essay/Biodiversity-3283.aspx Genetic Engineering <center><b>Accepting the Possibilities: A Research Paper on Genetic Engineering</b></center> Science is a creature that continues to evolve at a much higher rate than the beings that gave it birth. The transformation time from tree-shrew, to ape, to human far exceeds the time from analytical engine, to calculator, to computer. But science, in the past, has always remained distant. It has allowed for advances in production, transportation, and even entertainment, but never in history will science be able to so deeply affect our lives as genetic engineering will undoubtedly do. With the birth of this new technology, scientific extremists and anti-technologists have risen in arms to block its budding future. Spreading fear by misinterpretation of facts, they promote their hidden agendas in the halls of the United States congress. Genetic engineering is a safe and powerful tool that will yield unprecedented results, specifically in the field of medicine. It will usher in a world where gene defects, bacterial disease, and even aging are a thing of the past. By understanding genetic engineering and its history, discovering its possibilities, and answering the moral and safety questions it brings forth, the blanket of fear covering this remarkable technical miracle can be lifted. The first step to understanding genetic engineering, and embracing its possibilities for society, is to obtain a rough knowledge base of its history and method. The basis for altering the evolutionary process is dependant on the understanding of how individuals pass on characteristics to their offspring. Genetics achieved its first foothold on the secrets of nature's evolutionary process when an Austrian monk named Gregor Mendel developed the first "laws of heredity." Using these laws, scientists studied the characteristics of organisms for most of the next one hundred years following Mendel's discovery. These early studies concluded that each organism has two sets of character determinants, or genes (Stableford 16). For instance, in regards to eye color, a child could receive one set of genes from his father that were encoded one blue, and the other brown. The same child could also receive two brown genes from his mother. The conclusion for this inheritance would be the child has a three in four chance of having brown eyes, and a one in three chance of having blue eyes (Stableford 16). Genes are transmitted through chromosomes, which reside in the nucleus of every living organism's cells. Each chromosome is made up of fine strands of deoxyribonucleic acids, 2001-04-15T14:00:00-04:00 http://75.150.148.189/free-essay/Genetic-Engineering-3211.aspx Differences In Animal Phyla Because they are grouped in the same kingdom, the nine animal phyla share the same fundamental characteristics- they are multicellular, heterotrophic eukaryotes that obtain nutrients through ingestion, they lack cell walls, they have nervous tissue and muscle tissue, and they reproduce sexually and have a unique embryonic life cycle. However, the animal phyla have a great number of differences as well. Some are visible to the naked eye, while others are less obvious, and still more cannot even be seen after embryonic development. What are these differences, and how did they shape the development of the phylogenetic tree? In animals, the embryo becomes layered through the process of gastrulation, or the formation of the two layered, cup-shaped embryonic stage from a blastula. These layers are called germ layers. Most animals are triploblastic, meaning they have three germs layers. These are the ectoderm, the endoderm, and the mesoderm. The ectoderm is the outermost layers which forms the body’s covering and the central nervous system. The endoderm is the innermost germ layer. It forms the digestive tube and gives rise to most organs. The third layer, the mesoderm, exists between the endoderm and ectoderm. It forms the muscles and most other organs towards the upper layer of the animal. Diploblastic animals, or animals with only two germ layers, lack mesoderm. There are only two diploblastic phyla: Porifera, the sponges, and Cnidaria, the “bag animals.” All other animals are triploblastic. In fact, sponges are such simple animals that they lack even true tissue. They are in the parazoan category (parazoans lack true tissue). Sponges are the only animals that are parazoans- all other phyla are eumetaozoans, animals with true tissue. The presence or absence of a body cavity is important in distinguishing different phyla. A body cavity is a fluid lined space separating the digestive tract from the outer body wall. It can act as a shock absorber, protecting the organs, regulate circulation, and allow room for organ growth. Most animals that have a body cavity also have a complete digestive tract. Acoelomates lack a body cavity altogether. An example of an acoelomate is a flatworm. Pseuodocoelomates have a body cavity, but it is not completely lined with mesoderm. The roundworm is an example of a pseudocoelomate. The eucoelomates have a true body cavity. It is completely lined with mesoderm. A segmented worm, such as an earthworm, is an example of a eucoelomate. The 2001-03-05T13:00:00-05:00 http://75.150.148.189/free-essay/Differences-In-Animal-Phyla-2995.aspx Sickel Cell Anemia Sickle Cell anemia is a group of inherited red blood cell disorders, or a collection of recessive genetic disorders characterized by a hemoglobin variant called Hb S. Normal red blood cells are round like doughnuts, and they move through small blood tubes in the body to deliver oxygen. Sickle red blood cells become hard, sticky and shaped like sickles used to cut wheat. When these hard and pointed red cells go through the small blood tube, they clog the flow and break apart. This can cause pain, damage and a low blood count, or anemia. There is a substance in the red cell called hemoglobin that carries oxygen inside the cell. One little change in this substance causes the hemoglobin to form long hard rods in the red cell when it gives away oxygen. These rigid rods change the red cell into a sickle shape. For such a miniscule mistake, the consequences are tragic. At the time of conception, a person receives one set of genes from the mother and a corresponding set of genes from the father. Sickle cell disease is a condition that is determined by a single pair of genes. The genes are those which control the production of hemoglobin in red cells. It is a member of the globin gene family, a group of genes involved in oxygen transport, and hemoglobin binds oxygen in the lungs and delivers it to the other tissues. Most people have two normal genes for hemoglobin. Some people carry one normal gene and one gene for sickle hemoglobin. This is called "sickle cell trait". These people are normal in almost all respects. Problems from having a single sickle cell gene develop only under very unusual conditions. People who inherit two genes for sickle hemoglobin (one from each parent) have sickle cell disease. It is believed that individuals with African and Mediterranean ancestry have unusually high frequency of sickle cell trait due to the reduced mortality from malaria infections when compared with individuals who do not carry the hemoglobin variant Red blood cells carrying the abnormal gene (hemoglobin S) travel normally through circulation until they are deoxygenated. When this happens the hemoglobin S molecules form long, rigid rods, causing the normally donut-shaped cells to stiffen and distort into a sickle shape. These sickle cells have a very hard time moving through the small capillaries. As blood flow slows, the cells lining the vessel 2001-02-27T13:00:00-05:00 http://75.150.148.189/free-essay/Sickel-Cell-Anemia-2944.aspx Goldenrod Goldenrod is common name for certain related plants of the composite family. The Canada goldenrod 2001-02-27T13:00:00-05:00 http://75.150.148.189/free-essay/Goldenrod-2945.aspx The nature of disease causing organisms and the mechanisms employed to combat them <center><b>The nature of DISEASE CAUSING ORGANISMS and the mechanisms employed by man to combat these organisms.</b></center> What is disease? A disease is a disturbance in the normal structure or function of an organism, group of organisms or the entire body. Diseases affect different organisms in different ways, they may be temporary, they may be chronic, or they may be terminal. They may even be localized or widespread through an entire body. Many diseases have been eradicated, but, some have no cure. Humans and other vertebrates have a system of specific immunity to combat disease. Some disease causing organisms invade body tissues and then destroy them, while others setup a symbiotic relationship with the cells. Most communicable diseases are caused by microorganisms or larger parasites that are commonly called germs, most scientists call them pathogens. What kinds of disease are there, that are caused by organisms? -Infectious disease- caused by living organisms, can be passed by contact. -Viral disease- caused by viruses, difficult to treat because viruses are non-living -Fungal disease- usually cause mild infections, difficult to treat -Protozoan disease- the "tropical diseases" caused by protozoa -Worm infections- mostly in the tropics, worms inside body causing damage -Diseases can be caused by a wide variety of bacteria, viruses, fungi, protozoans, and parasitic worms. Some sferre some disease causing organisms, and how do they affect plants? Plant diseases can be caused by microorganisms, parasitic flowering plants, nematodes, viruses, or adverse environmental conditions. Bacterial diseases are marked by symptoms such as soft rot, leaf spot, wilt of leaves and roots, cankers, leaf and twig blight, and gall formation. Most plant diseases are caused by fungi. Fungal diseases have been documented on since biblical times. Fungal diseases are characterized by leaf spots, ulcerous lesions, blights, powdery mildew, cankers, root rots, wilts, and club root. Viral diseases are infectious and spread largely by insects. All economic plants suffer from one or more viral diseases. Symptoms include mosaic patterns, yellowing of foliage, vein clearing, ring spots, stunting and premature death, malformations and overgrowth. Nematodes, or roundworms, are a large cause of disease in plants. They live in and cause damage to the roots, stems, leaves, and bulbs of plants. Non parasitic diseases are attributed to weather conditions. What are some disease causing organisms that affect animals? These diseases are of great importance to humans, they could affect animals that are used for, or produce food. Some of these diseases may even be transmitted to 2001-02-25T13:00:00-05:00 http://75.150.148.189/free-essay/The-nature-of-disease-causing-organisms-and-the-mechanisms-employed-to-combat-them-2906.aspx Bryophyte and Pteropyte Life Cycles - A Compare/Contrast Although Bryophytes and Pterophytes are both plant divisions with a common ancestor, they have little in common. While Bryophytes (mosses) are generally nonvascular and very short in height, Pterophytes (ferns) are vascular plants that usually grow much taller than mosses. While the dominant generation in mosses is the gametophyte, ferns exhibit the sporophyte generation. The details of their alternations of generation vary as well, although both have diploid and haploid stages. Alteration of generations is defined as a life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte. Meiosis in mosses produces haploid spores. This process occurs in a sporangium, a capsule in fungi and plants in which meiosis takes place and haploid spores develop. After fertilization, the sporophyte zygote grows out of the parent gametophyte. At the end of this stalk is the sporangium. Meiosis occurs and the haploid spores disperse. In ferns, the mature sporophyte (2N) has small spots on the undersides of its leaves. These are clusters of the Pterophyte sporangia, called sori. As in mosses, meiosis occurs in the sporangia, which then release spores, continuing the cycle. Mitosis in Bryophytes begins germination, or growth. It directly follows meiosis. As mitotic division continues, protonemata (1N) are formed. They grow until they are mature gametophytes. In Pterophytes, mitosis occurs directly after fertilization. The zygote divides and grows until it peeks out of the parent gametophyte, then it matures until it can release its own spores. Mosses exhibit the embryophyte condition, which means their gametes develop with protective sheaths of cells. This was an adaptation that allowed plants to become hardier. Mosses have two sexes of gametangia; the male gametangium is called an antheridium, and the female is called an archegonium. Eggs are produced in the archegonium and sperm in the antheridium. In order for fertilization to take place, the sperm must swim through moisture to the archegonium. This is why mosses must live in damp environments to survive- they cannot reproduce without moisture. The zygote develops within the archegonial cavity. Ferns are usually homosporous as well (there is a single type of spore; the gametophyte is bisexual). In ferns, the archegonia and antheridia mature at different times, which means there is cross fertilization between gametophytes and thus more genetic variation. Sperm from the antheridia swim to the archegonia where the zygote develops. Like mosses, ferns also need a 2001-02-10T13:00:00-05:00 http://75.150.148.189/free-essay/Bryophyte-and-Pteropyte-Life-Cycles-A-Compare-Contrast-2845.aspx Hardy-Weinburg Equilibrium The Hardy-Weinberg theorem states that the frequency of alleles and genotypes in a population’s gene pool remain constant over the generations unless acted upon by agents other than sexual recombination. For example, take a population of mice that consists of 1,000 members. A specific allele, albino allele, is recessive within this species. 80% of the population expresses the normal phenotype- brown coloring, while the remaining 20% are albino. 640 members of the population have the genotype AA, 320 have Aa, and 40 have aa. If completely random mating were to occur, there would be an 80% chance that a gamete would bear the normal allele, A, and a 20% chance that the gamete would bear the albino allele, a. The resulting offspring will display the following genotype ratios: AA will have 64%, Aa 32% (the chance of the offspring having the A allele is 96%), and aa 4%. The offspring have the same genotype ratio as their parents. This example was one of Hardy-Weinberg equilibrium. The next generation will express the same genotype ratio as their parents, and so on. But what exactly is needed to create Hardy-Weinberg equilibrium? (Basically, a population in Hardy-Weinberg equilibrium s not evolving in any way.) Five specific factors are needed to create Hardy-Weinberg equilibrium within a population- a very large population, isolation from other populations, no net mutations, random mating, and no natural selection. The first element needed to create Hardy-Weinberg equilibrium is a very large population size. The larger the population, the less likely it is for genetic drift to occur. Genetic drift is a chance fluctuation in the gene pool that may change the frequencies of alleles. A large population can better represent the gene pool of the previous generation than a small one. In order to completely eliminate all chances of genetic drift, a population would have to be infinitely large. Thus, we can see here that perfect Hardy-Weinberg equilibrium, which has no changes in the frequency of alleles, would require no genetic drift at all, and genetic drift itself is only possible in a population of infinite size. There are two types of genetic drift- the bottleneck effect and the founder effect. Both severely decrease the variability within a population, altering the frequencies of alleles and thus making Hardy-Weinberg equilibrium impossible. If a disaster occurs in a population, killing off many members, the surviving members will not be representative of the 2001-02-10T13:00:00-05:00 http://75.150.148.189/free-essay/Hardy-Weinburg-Equilibrium-2852.aspx The Human Genome Project A genome is all the DNA in an organism, including it’s genes. Genes carry information for making all the proteins required by all organisms. These proteins determine, among other things, how the organism looks, acts, processes and fights infections. DNA is made up of four similar chemicals (bases, adenine <A>, Thymine <T>, cytosine <C>, and guanine <G>) that are repeated millions or billions of times throughout a genome. The human genome has three billion base pairs. The order of these base pairs are extremely important and determine everything in an organism. The Human Genome Project started in the mid-1980’s and was discussed widely throughout the scientific community and public press in the last years of the decade. In the United States, DOE first and soon afterward NIH were the main research agencies within the US government responsible for developing and planning the project. By 1988, the two agencies were working together, and their relationship was formalized by the signing of a Memorandum of Understanding, to coordinate research and technical activities related to the human genome. The initial planning process culminated in 1990 with the publication of a joint research plan. The Human Genome Project’s ultimate goal is to discover all the more than 80,000 human genes and render them for further biological study. To facilitate the future interpretation of human gene function, parallel studies are being carried out on selected model organisms. Smaller goals include, to identify all the approximately 100,000 genes in human DNA, to determine the sequences of the three billion chemical bases that make up human DNA, to store this information in databases, to develop faster and more efficient sequencing technologies, to develop tools for data analysis, and to address the ethical, legal and social issues (ELSI) that may arise from the project. The massive amount of data and related technologies generated by the HGP and other genomic research presents a wide array of commercial opportunities. These opportunities range from medicine and food to energy and environmental resources. Older companies are racing to retool and newer companies are seeking parts in the information revolution with DNA at it’s core. IMB, Compaq, DuPoint, and other big pharmaceutical companies are among those interested in the potential for targeting and applying genome data. In HGP there are two types of sequences, the draft and the high quality. To get the draft sequence, scientist determine the order of base pairs in each chromosomal area at least four to 2001-02-08T13:00:00-05:00 http://75.150.148.189/free-essay/The-Human-Genome-Project-2842.aspx Cell Membrane/ Electron Transport Chain / Biochemical Pathway 1. The cell membrane structure is vital to the life of the cell. The cell membrane is shaped as having a phosphate head at the very outer surface, and two fatty acid tails hanging from it. The membrane is double, so at the tip of the fatty acid tails, there are two more fatty acid tails attached to another phosphate head. This is what it looks like: The reason the cell membrane is shaped like this is mainly to control the water flow in and out of the cell. Water is very important to the cell: if too much water enters the cell, the cell will explode, and if too much water leaves the cell, the cell will shrivel up and die. This is how the cell membrane controls water flow: the phosphate heads are polar, and slightly attract water. However, the fatty acid tails in between are non polar, and repel water, so the fatty acid tails prevent too much water from entering or leaving the cell. With this tough membrane, there has to be a way for things to enter the cell. This is where the channel proteins come in. They act as gateways to the cell. There are many ways to enter the cell. Some ways require energy, while others don’t. The ways that require energy are put into a category called active transport, while the ways that don’t require energy are put into a category called passive transport. An example of active transport is the proton pump. The proton pump is an integral part of chemiosmosis, and it pumps protons from an area of low concentration to an area of high concentration. This requires energy since things like to move from an area of high concentration to an area of low concentration. An example of passive transport is facilitated diffusion. This is very easy since the particle is moving from an area of high concentration to an area of low concentration and through a channel protein made exactly for its size and shape. 2. These membranes are very important to the electron transport chain. This is because they house the membrane proteins that make up the electron transport chain. The two electron transport chains are similar in that they both make ATP by chemiosmosis, and they are different in the fact that they pump protons in different directions: the electron transport chain in the thylakoid layer pumps 2001-02-06T13:00:00-05:00 http://75.150.148.189/free-essay/Cell-Membrane-Electron-Transport-Chain-Biochemical-Pathway-2837.aspx Spontaneous Generation From the time of the Ancient Romans, through the Middle Ages, and until the late nineteenth century, it was generally accepted that life arose spontaneously from non-living matter. Such "spontaneous generation" appeared to occur primarily in decaying matter. For example, a seventeenth century idea for the spontaneous generation of mice required placing sweaty underwear and husks of wheat in an open-mouthed jar. Then, waiting for about 21 days, during which time it was said that the sweat from the underwear would penetrate the husks of wheat, changing them into mice. Although that idea may seem ridiculous today, that and other ideas like it were believed and accepted during that time, which was not too long ago. The first serious attack on the idea of spontaneous generation was made in 1668 by Francesco Redi, an Italian physician and poet. At that time, it was thought that maggots arose spontaneously in rotting meat. Redi believed that maggots developed from eggs laid by flies after observing that they had different developmental stages.. To test his hypothesis, he set out meat in a variety of flasks, some open to the air, some sealed completely, and others covered with gauze. As he had expected, maggots appeared only in the open flasks in which the flies could reach the meat and lay their eggs. This was one of the first examples of an experiment in which controls are used. In spite of his well-executed experiment, the belief in spontaneous generation remained strong, and even Redi continued to believe it occurred under some circumstances. The invention of the microscope encouraged this silly belief. Microscopes revealed a whole new world of organisms that appeared to arise spontaneously. It was quickly learned that to create "animalcules," as the organisms were called, you needed only to place hay in water and wait a few days before examining your new creations under the microscope. The debate over spontaneous generation continued for centuries. In 1745, John Needham, an English clergyman, proposed what he considered the definitive experiment. Everyone knew that boiling killed microorganisms, so he proposed to test whether or not microorganisms appeared spontaneously after boiling. He boiled chicken broth, put it into a flask, sealed it, and waited - sure enough, microorganisms grew. Needham claimed victory for spontaneous generation. An Italian priest, Lazzaro Spallanzani, was not convinced, and he suggested that perhaps the microorganisms had entered the broth from the air after 2001-01-27T13:00:00-05:00 http://75.150.148.189/free-essay/Spontaneous-Generation-2786.aspx Taxonomy This following report will show you the classifications and information of the Jaguar, Tiger Shark, Earth Worm, Red Wood, and Killer Whale.<table border="1"><tr>Category</td><td>Jaguar</td><td>Tiger Shark</td><td>Earth Worm</td><td>Red Wood</td><td>Killer Whale.</td></tr><tr>Kingdom-</td><td>Animalia</td><td>Animalia</td><td>Animalia </td><td>Plantae</td><td>Animalia. </td></tr><tr>Phylum-</td><td>Chordata</td><td>Chordata</td><td>Annelida</td><td>Embryophyta</td><td>Chordata</td></tr><tr>Class-</td><td>Mammalia</td><td>Chondrichthyes</td><td>Oligochaeta</td><td>Coniferopsida</td><td>Mammalia.</td></tr><tr>Order-</td><td>Carnivora</td><td>Carcharhiniformes</td><td>Haplotaxida</td><td>Coniferales</td><td>Cetacea</td></tr><tr>Family-</td><td>Felidae</td><td>Carcharhinidae</td><td>Megasclolecidae</td><td>cupressaceae</td><td>Delphinidae.</td></tr><tr>Genus-</td><td>Panthera</td><td>Galecoerdo</td><td>Pheretima</td><td>Sequoia</td><td>Orcinus.</td></tr><tr>Species- Panthera onca</td><td>Galecoerdo covier</td><td>Pheretima Sieboldi</td><td>Sequoia sempervirenes</td><td>Orcinus orca</td></tr></table><b>THE JAGUAR</b>The largest member of the cat family found on the American continents is the jaguar. Its average length is between 6 and 7 feet (about 2 meters). It has a large head and massive legs. Jaguars vary in color, but usually they are yellowish brown, with black spots like those of the leopard. The jaguar's spots, however, are larger and more angular. The jaguar was once found from the southern United States to Uruguay, but now it is a species in danger of extinction and survives mainly in undeveloped rain forests in Central and South America. The largest known population exists in the Amazon rain forest. Although jaguars usually stalk or ambush their prey, which consists mostly of peccaries, they are excellent swimmers and sometimes take capybaras, tapirs, crocodiles, and fish.<b>TIGER SHARK</b>Sometimes called Leopard shark cause of his markings. This Texas species is known to be a man-eater. They are the largest species of shark to inhabit Texas waters they are the most dangerous. The markings that they derive their name from are more pronounced on the younger ones and fade out the older the shark gets. This massive 1,500-pound animal eats just about anything he wants too. This includes just about everything though from stingrays, squid, fish, smaller sharks, seagulls, and even humans!<b>EARTHWORM</b>The earthworm has a cylindrically shaped, segmented body that tapers off at both ends. It has a well-developed digestive, circulatory, respiratory and nervous system. The size can range any where from a length of a few centimeters to a length of up to 11 feet. Earthworms can burrow under ground with considerable speed especially in loose soil. What is really interesting is the if you cut a worm in half it stays alive. <b>RED WOOD</b>The towering redwood is the tallest of all trees. During a lifetime of up to 2,000 years it may grow to nearly 400 feet (120 meters) high and more than 30 feet (9 meters) thick at the base. Its close relative, the big tree, or giant sequoia, is among the oldest of the forest trees--it may live for 3,000 years or more. It reaches heights of more than 250 feet (75 meters) and may have a trunk diameter of 2000-10-30T13:00:00-04:00 http://75.150.148.189/free-essay/Taxonomy-2430.aspx The Eye and Laser Eye Surgery <b>A Functioning Eye (Emmetropia)</b> The eye is the organ of sight. It is used in almost everything we do, from playing sport to reading. A normal and well functioning eye can focus objects and images, both near and far, perceive depth and adapt to changes in light. The perception of depth is due to having two separate eyes creating two separate images, while the ability to adapt to light change is attributed to the iris and the dilator muscles. However these two aspects of the eye are not involved in laser eye surgery and will not be discussed in reference. The focusing of objects and images is very much part of laser eye surgery. In order for a clear visual image to be formed the image must come to a point on the retina. Light rays do not normally travel toward each other, usually the light rays either travel outwards or almost parallel, for this reason the light rays must be refracted. The cornea is the primary place of refraction, the “bent” light rays then travel through the aqueous humor and the pupil to the lens. Here the light is one again refracted even closer together, the light then goes through the vitreous humor and is projected onto the retina. The focus of the lens should be aimed at the fovea centralis (a tiny pit in the middle of the macula). It is in this region that vision is most sharp. For this reason, instead of simply staring at one point the eye must constantly “scan” the area to focus the whole object or image. In order to accommodate the changing distances of the object or image the lens in the eye has to adjust, becoming thinner to focus distant objects and fatter to focus near by objects. This process, of changing the lens thickness is known as accommodation. In order for this to occur the ciliary muscles contract and relax. The contraction fattens the lens and the relaxation stretches the lens. The eye functions on much the same principle as a camera. The iris, or coloured portion of the eye, acts as a shutter to regulate the amount of light admitted to the eye. The cornea (the clear window at the front of the eye) and the lens (located behind the pupil) serve to focus light rays from the object viewed onto the retina at the back of the eye. 2000-10-26T14:00:00-04:00 http://75.150.148.189/free-essay/The-Eye-and-Laser-Eye-Surgery-2414.aspx The Importance of Water in Living Organisms Water has importance inside cells and externally. This may be because it has interesting chemical and physical properties; it can be found naturally in all three of its states. However its molecules are bonded together by hydrogen bonds, this raises its melting and boiling points, i.e. its boiling point would be -120¢ªC rather than 100¢ªC. Also because it contains slightly negatively charged oxygen atoms and slightly positively charged hydrogen atoms making it polar. Water has been called a universal solvent because of it polarity. This means it can easily ionise substances, Many compounds, whether ionic, polar or covalent will dissolve in it, therefore more reactions take place while in solution with water. Often in organisms substances must be in solution and water is the solvent. Plants can only obtain mineral salts in solution and human digestion will only dissolve soluble foods, meaning large starch molecules must be broken down into soluble sugars. Also many organisms living in water spend most of their time underwater, yet they require oxygen to respire, and as water is such a good solvent the required oxygen gas is dissolved in the water. Water is the most abundant component in any organism, the lowest is 20% in seeds, while jellyfish are 99% (hence the transparency). It plays vital roles in the metabolism of all cells and in photosynthesis (providing raw materials) in plant cells. In all cells water is used for; hydrolysis, the breakdown of a substance by water, e.g. polysaccharides to monosaccharides, forming a glycosidic bond; a medium for chemical reactions, due to its properties as a solvent; the diffusion and osmosis of substances, e.g. gaseous exchange, which need to be moist as the exchange takes place in solution, therefore there is water in the lungs or in mesophyll cells (in plants) . It is also used on a much larger scale for transport. Blood is mostly water, and is used to transport food, hormones, waste products (ammonia and urea) and oxygen, similarly in plants, sap is used to transport food and other substances. These substances all easily dissolve in water and then can be transported, whether it be oxygen to tissues, or hormones to various organs. Water is also used during fertilization when sperm must reach the ovum, the sperm is transported in semen, which is mostly water. Due to water's viscosity it is a useful lubricant, as it reduces friction giving free and easy movement. For example 2000-10-14T14:00:00-04:00 http://75.150.148.189/free-essay/The-Importance-of-Water-in-Living-Organisms-2366.aspx On Dis-ease <center><a href="http://www.geocities.com/vaksam/">Sam Vaknin's Psychology, Philosophy, Economics and Foreign Affairs Web Sites</a></center> We are all terminally ill. It is a matter of time before we all die. Aging and death remain almost as mysterious as ever. We feel awed and uncomfortable when we contemplate these twin afflictions. Indeed, the very word denoting illness contains its own best definition: dis-ease. A mental component of lack of well being must exist SUBJECTIVELY. The person must FEEL bad, must experience discomfiture for his condition to qualify as a disease. To this extent, we are justified in classifying all dieases "spiritual" or "mental". Is there any other way of distinguishing health from sickness - a way that does NOT depend on the report tha the patient provides regarding his subjective experience? Some diseases are manifest and others are latent or immanent. Genetic diseases can exist - unmanifested - for generations. This raises the philosophical problem or whether a potential disease IS a disease? Are AIDS and Hemophilia carriers - sick? Should they be treated, ethically speaking? They experience no dis-ease, they report no symptoms, no signs are evident. On what moral grounds can we commit them to treatment? On the grounds of the "greater benefit" is the common response. Carriers threaten others and must be isolated or otherwise neutered. The threat inherent in them must be eradicated. This is a dangerous moral precedent. All kinds of people threaten our well-being: unsettling ideologists, the mentally handicapped, many politicians. Why should we single out our physical well-being as worthy of a privileged moral status? Why is our mental well being, for instance, of less import? Moreover, the distinction between the psychic and the physical is hotly disputed, philosophically. The psychophysical problem is as intractable today as it ever was (if not more so). It is beyond doubt that the physical affects the mental and the other way around. This is what disciplines like psychiatry are all about. The ability to control "autonomous" bodily functions (such as heartbeat) and mental reactions to pathogenes of the brain are proof of the artificialness of this distinction. It is a result of the reductionist view of nature as divisible and summable. The sum of the parts, alas, is not always the whole and there is no such thing as an infinite set of the rules of nature, only an asymptotic approximation of it. The distinction between the patient and the outside world 2000-10-09T14:00:00-04:00 http://75.150.148.189/free-essay/On-Dis-ease-2318.aspx Bipolar Disorder: Cause of Great Madness or Great Genius? Is bipolar disorder the cause of great madness or great genius? The symptoms of this mental illness may also be considered as the driving forces behind some of the most gifted and talented people to grace our society. Although individuals with this illness may have some obstacles to overcome, it can be accomplished. With all of the treatment programs that are widely available, people have many options and methods to turn to for help. Bipolar disorder, also referred to as manic depression, is a mood disorder. A person with bipolar disorder will have extreme mood shifts between mania, a state of highly elevated euphoric feelings, and depression, a state of despondency and despair. These shifts can take weeks, days, or even minutes to happen. The period between shifts will vary for each individual, depending on the severity of the disorder (Williams & Wilkins, 1999, pp. 5-35). Approximately two percent of adults have this mental illness, and about fifteen percent of those adults will attempt suicide. Bipolar disorder affects both men and women and the affected rates are similar between different cultures and countries. Most people with bipolar disorder experience their first mood episode in their twenties, although it is not uncommon to experience the first episode during childhood or in late life (Bi-polar Disorder: Innovative Research in Health, 2000). Bipolar disorder is not a curable disorder, although it is treatable. Bipolar is "among the most treatable of the psychiatric illnesses" (Manic-Depressive/Bipolar Disorder, 2000). It is important for people who believe that they may need help to seek it as soon as possible because the earlier that bipolar disorder can be diagnosed the earlier treatments can start. Even after experiencing an episode, even after sensing that something may be wrong, individuals who seek help may not initially receive the correct diagnosis from a medical professional. Because of the similarity of symptoms, bipolar disorder may initially be misdiagnosed as panic disorder, schizophrenia, or attention deficit disorder (Bi-polar Disorder: Innovative Research in Health, 2000). Bipolar may also be difficult to diagnose because the person seeking help may not be telling the doctor everything the doctor needs to know to correctly identify the problem. Medical professionals may only diagnose a person as having depression because they have no knowledge of the excessive enthusiasm that the patient feels. It is important for individuals seeking medical help to be accurate and thorough in describing their feelings or symptoms 2000-10-07T14:00:00-04:00 http://75.150.148.189/free-essay/Bipolar-Disorder-Cause-of-Great-Madness-or-Great-Genius-2298.aspx Born Aliens <center><a href="http://www.geocities.com/vaksam/">Sam Vaknin's Psychology, Philosophy, Economics and Foreign Affairs Web Sites</a></center> Neonates have no psychology. If operated upon, for instance, they are not supposed to show signs of trauma later on in life. Birth, according to this school of thought is of no psychological consequence to the newborn baby. It is immeasurably more important to his "primary caregiver" (mother) and to her supporters (read: father and other members of the family). It is through them that the baby is, supposedly, effected. This effect is evident in his (I will use the male form only for convenience's sake) ability to bond. The late Karl Sagan professed to possess the diametrically opposed view when he compared the process of death to that of being born. He was commenting upon the numerous testimonies of people brought back to life following their confirmed, clinical death. Most of them shared an experience of traversing a dark tunnel. A combination of soft light and soothing voices and the figures of their deceased nearest and dearest awaited them at the end of this tunnel. All those who experienced it described the light as the manifestation of an omnipotent, benevolent being. The tunnel - suggested Sagan - is a rendition of the mother's tract. The process of birth involves gradual exposure to light and to the figures of humans. Clinical death experiences only recreate birth experiences. The womb is a self-contained though open (not self-sufficient) ecosystem. The Baby's Planet is spatially confined, almost devoid of light and homeostatic. The fetus breathes liquid oxygen, rather than the gaseous variant. He is subjected to an unending barrage of noises, most of them rhythmical. Otherwise, there are very few stimuli to elicit any of his fixed action responses. There, dependent and protected, his world lacks the most evident features of ours. There are no dimensions where there is no light. There is no "inside" and "outside", "self" and "others", "extension" and "main body", "here" and "there". Our Planet is exactly converse. There could be no greater disparity. In this sense - and it is not a restricted sense at all - the baby is an alien. He has to train himself and to learn to become human. Kittens, whose eyes were tied immediately after birth - could not "see" straight lines and kept tumbling over tightly strung cords. Even sense data involve some modicum and modes of conceptualization (see: "Appendix 5 - 2000-10-05T14:00:00-04:00 http://75.150.148.189/free-essay/Born-Aliens-2308.aspx Ebola: Human Soup Maker I chose to do my report of the Ebola Virus because it is a very deadly, and it’s a virus that isn’t publicized much in newspapers and televisions. So I think it’s a good choice. The Ebola virus is one of the worlds most deadly viruses, in all of its many forms. The purpose of this essay is to explain the history, signs and symptoms of the Ebola virus. Between the years 425BC & 430BC Athens’ population was dramatically reduced when about 300,000 of its inhabitants died from some sickness. People now believe this sickness was Ebola. The first recorded outbreak of the Zaire string of the Ebola virus was in Zaire in the year 1976. Doctors didn’t know how to treat it, that also means they didn’t know how to contain it. The infected people would meet in public areas, and the virus would spread. In western Sudan, the same year, the Sudan string of the Ebola virus immerged with similar results. In both types of the Ebola virus, combined had 550 infections and 340 deaths, which is a 60% fatality rate. The viruses then laid dormant until 1979, when Sudan was hit again with a smaller infection rate of 34 infections and 22 deaths. As before the fatality rate was about 60%. In 1987 a new string of the Ebola virus was discovered. This string was called the Reston string. This string was air born and it was a mutation of the Zaire string. A group of monkeys that where infected got sent to Virginia from the Philippines. Luckily the string doesn’t infect Homo Sapiens. A lot of workers came in contact with the monkeys, and none of them died, or even showed signed of illness. In Kikwit, Zaire there was another outbreak in 1995. This time a patient was admitted to a hospital, the doctors thought he had Malaria. The surgeons decided to operate because of his worsening symptoms. The whole surgical team came in contact with the patients body fluids, and they were all infected. From this operating room, 293 cases were recorded and 233 deaths, which means a higher fatality rate. In the later part of 1995 another string of the Ebola virus was discovered. A Swiss researcher in West Africa was the first to get the Tai string of the Ebola virus. She got it from a chimpanzee in the Tai forest. She was taken to a hospital 2000-10-03T14:00:00-04:00 http://75.150.148.189/free-essay/Ebola-Human-Soup-Maker-2289.aspx Genetic Testing and Its Social Implications Probably, applied genetics’ most impacts on society are as a result of genetic tests. In general, genetic tests seek to detect some feature of a person’s genetic constitution. This feature can be a disease causing mutation or a marker DNA sequence used to detect presence of another gene. Obviously these procedures used for testing the status of DNA, RNA or chromosomes are included in genetic tests. What is more it is possible to include some protein based tests and classical medical examinations when they aim to detect inheritance of a trait. Genetic tests have been divided into four categories in this text, and they will be examined in greater detail later. These categories are: <li>Prenatal tests that are applied on fetuses during pregnancy. <li>Neonatal screening just after birth and career screening of marrying couples. <li>Testing for serious late-onset disease before the symptoms occur. <li>Testing to assess the probability of developing complex disease. There are a couple of considerations about genetic tests: 1. First of all, the tests should be reliable. When a positive or a negative result is obtained, we should be confident in that result with a confidence approaching 100%. To achieve such a high accuracy is not as easy as it may at first appear to be. Meiotic recombinations that always occur take place during gamete generation, may separate a disease-associated gene and a marker DNA sequence which is used to detect mutated genes. False positive or negative results could be obtained. In addition, genetic tests look for the most common mutations that cause the disease. For example, a test would detect CFTR?F508 (Cystic Fibrosis Transmembrane Receptor) mutation, however it is not possible to detect infinite number of other mutations. Therefore, a genetic test can give such results so that the physician is convinced that his patient is normal while he is affected by an undetectable mutation. New tests are continuously being developed. Doctors and genetic counselors who will use these tests in the future, should be well informed about newly emerging tests. 2. Extremely accurate genetic tests can only be developed by thorough experimentation on human subjects. Although there is generally no physiological risk in experimenting a person, the subjects should be informed that the applied test is not entirely reliable and in experimentation state. Informing subjects of experimentation is an obligation set by the Nuremberg Code. Just after World War II it was discovered that unethical 2000-06-23T14:00:00-04:00 http://75.150.148.189/free-essay/Genetic-Testing-and-Its-Social-Implications-2124.aspx Flagella and Cilia <b>Flagella</b> Flagella are necessary for the active movement of bacterial cells and protozoa. Flagella are single, whip-like structures that propel an 2000-05-15T14:00:00-04:00 http://75.150.148.189/free-essay/Flagella-and-Cilia-1964.aspx Body Composition According to Mosbey's Medical, Nursing, & Allied Health Dictionary, Body Composition is defined as the relative proportions of protein, fat, water, and mineral components in the body. It varies as a result of differences in body density and degree of obesity. Basically body composition describes the percentages of fat, bone, and muscle in a persons body. The percentages of body fat a person has determines their overall health and fitness when compared to factors like age, weight, and sex. Body composition also contributes to a persons overall appearance. A healthy male should have about12 to 18 percent of fat. Females should have around 14 to 20 percent. Any thing over or under these percentages would be considered unhealthy.The term's weight and fat are usually used in the same context when discussing physical fitness. Under certain circumstances, being overweight doesn't mean that a person is unhealthy. A person could be in good physical shape but considered overweight because they have excess muscle. People with a lot of muscle mass usually have body weight, which is disproportional to their height. Having a high percentage of fat is unhealthy because it can cause heart disease, high blood pressure, and diabetes.It is important to know your body fat percentage because it can help you put together a realistic exercise program with goals that are attainable. A good exercise program incorporates both aerobic exercises, which burn fat and anaerobic exercises, which build muscle. It is healthier to turn fat into muscle instead of just trying to loose weight without thinking about gaining strength. The best way for a person to change his or her body composition is to improve their fitness levels. Fitness has different meanings to different people. Some people define fitness as having a small waistline. Other people may feel that fitness is the ability to bench-press their body weight ten times. And other people may feel that fitness is just being free from sickness. True fitness is a balance of all of the components of health. These components include aerobic endurance, muscular strength, muscular endurance, flexibility, and body composition. <b>Sources</b><li><a href="http://rcc.webpoint.com/fitness/combasic.htm">http://rcc.webpoint.com/fitness/combasic.htm</a><li>Mosby's Medical, Nursing, & Allied Health Dictionary, Edition 5, 1998 p. 134E<li>Werner W.K. Hoeger and Sharon A. Hoeger, 1998, Lifetime Physical Fitness & Wellness, 1998 by Morton 2000-05-03T14:00:00-04:00 http://75.150.148.189/free-essay/Body-Composition-1911.aspx Obsessive compulsive disorder (OCD) Approximately five million people in the U.S., or about one in every 50 Americans, suffer from OCD. That’s about 2%, a substantial number of sufferers. It affects men, women, and children, as well as people of all races, religions, and socioeconomic backgrounds. OCD is an anxiety disorder characterized by symptoms that can include powerful, unwanted, or recurrent thoughts and/or compulsive, repetitive behaviors. Some of the most common obsessions are: <li>Fear of contamination <li>Fear of causing harm to another <li>Fear of making a mistake <li>Fear of behaving in a socially unacceptable manner <li>Need for symmetry or exactness <li>Excessive doubt Some of the most common compulsions may include: <li>Cleaning/Washing <li>Checking <li>Arranging/Organizing <li>Collecting/Hoarding <li>Counting/Repeating Obsessions are unwanted, recurrent and unpleasant thoughts that cause anxiety. Compulsions are repetitive, ritualistic behaviors that the person feels driven to perform to decrease anxiety. At least 80 percent of patients with OCD have both obsessions and compulsions. OCD appears to be caused by increased activity in the orbital frontal cortex and caudate nucleus of the brain. OCD may also involve abnormal functioning of the neurotransmitter seratonin in the brain. Stress does not cause OCD; however, a stressful event can trigger the disorder. There are no hard facts to tell how OCD is obtained. OCD is thought to be a genetic disorder. This idea has plenty of evidence and is believed by most doctors. The chemical imbalance in the Brain is an imbalance of Seratonin and Dompamine. 80 percent of the people with OCD have another disorder called Tourettes Syndrome (TS). This syndrome is caused by the imbalance of Dompamine in the Brain. This causes the person to have muscular and/or verbal spasm which are called tics. Some people who are familiar with TS may think of people shaking wildly of cursing a lot, but that is only in a severe case. These are a couple of examples, or case studies, that I got off the internet. <b>I. Dick</b> Up until this year, Dick had done fairly well in school, played basketball, held down a part time job cleaning a fish plant, and spent most weekends with his girl friend. Over the last year, he has had to let most of this go. His girlfriend found someone who had more time, he quit his job, and he stopped going to basketball. He could barely get his schoolwork done. Why? It took him about three hours to get ready in 2000-04-25T14:00:00-04:00 http://75.150.148.189/free-essay/Obsessive-compulsive-disorder-OCD-1872.aspx Parkinson's Disease James Parkinson first discovered Parkinson's Disease in 1817. Parkinson's Disease is a common neurologic disorder for the elderly. It is a disorder of the brain characterized by shaking and difficulty with walking, movement, and coordination. This disease is associated with damage to a part of the brain that controls muscle movement. Parkinson's Disease is a chronic illness that is still being extensively studied. Parkinson's Disease has caused problems for many people in this world and plagued the elderly all over the world. Parkinson's disease still puzzles doctors and the causes are unknown. It is known that it is a non-communicable disease and may even be hereditary. Parkinson's disease is thought to be caused by external factors. Most of the cases of this disease are caused by progressive deterioration of the nerve cells, which control muscle movement. Dopamine, one of the substances used in the brain to transmit impulses, is produced in the area of deterioration. Without this vital dopamine nerve cells cannot properly transmit messages resulting in a loss of muscle function. Parkinson's Disease is a non-communicable disease and doctors have not yet found out whether or not it is a hereditary disease. Parkinson's Disease has many distinct symptoms. The symptoms are: <li>Muscle Rigidity <li>stiffness <li>difficulty bending arms or legs <li>unstable, stooped, or slumped-over posture <li>loss of balance <li>walking pattern changes <li>slow movements <li>difficulty beginning to walk <li>difficulty initiating any voluntary movement <li>small steps followed by the need to run to maintain balance <li>freezing of movement when the movement is stopped, inability to resume - movement <li>muscle aches and pains <li>shaking, tremors (varying degrees, may not be present) <li>characteristically occur at rest, may occur at any time <li>may become severe enough to interfere with activities <li>may be worse when tired, excited, or stressed <li>finger-thumb rubbing (pill-rolling tremors) may be present <li>changes in facial expression <li>reduced ability to show facial expressions <li>"mask" appearance to face <li>staring <li>may be unable to close mouth <li>reduced rate of blinking <li>voice/speech changes <li>slow speech <li>low-volume voice <li>monotone <li>difficulty speaking <li>loss of fine motor skills <li>difficulty writing, may be small and illegible <li>difficulty eating <li>difficulty with any activity that requires small movements <li>movement, uncontrolled- slow <li>frequent falls <li>decline in intellectual function (may occur, can be severe) <li>a variety of gastrointestinal symptoms, mainly constipation In order to diagnose whether or not a person has Parkinson's Disease based on the symptoms a physical examination can be preformed. Symptoms are often hard for a doctor to assess, especially in the elderly because 2000-04-16T14:00:00-04:00 http://75.150.148.189/free-essay/Parkinson-s-Disease-1860.aspx Genetic Engineering At the Roslin Institute in Edinburgh, Scotland, Dr. Keith Campbell, director of embryology at PPL therapeutics in Roslin, and his colleague Dr. Ian Wilmut worked together on a project to clone a sheep, Dolly, from adult cells. On February 22, 1997, they finally succeeded. Dolly was the only lamb born from 277 fusions of oocytes with udder cells. Wilmut says there were so many failures because it is difficult to ensure that the empty oocytes and the donor cell are at the same stage of the cell division cycle. To clone Dolly, basically scientists took an unfertilized egg cell, removed the nucleus, replaced it with cells taken from the organism to be cloned, put it into an empty egg cell which begins to develop as an embryo, and implanted this embryo into a mother, from which the clone was born. The fact that only 1 out of 277 attempts succeeded is a little scary when applied to human beings. If an attempt to clone a human led to that high of a death toll, then there would not be many supporters. According to Rifkin, in an extensive survey of all 106 clinical trials of experimental gene therapies conducted over the past five years involving more than 597 patients, a panel of experts convened by the NIG reported that "Clinical efficacy has not been definitively demonstrated at this time in any gene therapy protocol, despite anecdotal claims of successful therapy." (545). These results are also happening with people who are trying to get gene therapy. With these facts on the table, it would not be ideal to try to clone humans if cloning an animal took several hundred attempts and human gene therapy has had hundreds of failures as well. Humans are going way beyond their limits in the field of biotechnology in the world today. Until recently, these ideas were unheard of. Now with new technology, scientists are capable of changing an organism's genetic make-up. We are very eager to learn new things, however, this eagerness gets in the way of common sense all too often. As stated in Starr and Taggart's article, "we do not have the wisdom to bring about beneficial changes without causing great harm to ourselves or to the environment." (514). However, the naïve public may want to jump right into things, and scientists will not disagree. Scientists are messing with things that they should not be messing with. Once 2000-04-11T14:00:00-04:00 http://75.150.148.189/free-essay/Genetic-Engineering-1838.aspx Genetic Disorders Each year a number of children are born with biological defects that impair normal function. For THREE of the following conditions, discuss such aspects as the biological cause, the methods of treatment and possible means of detection and/or prevention. One lethal disorder inherited as a recessive allele is Tay-Sachs disease. This is caused by a dysfunctional enzyme that fails to break down brain lipids of a certain class. The symptoms usually become manifest a few months after birth. Some symptoms are seizures, blindness and degeneration of motor and mental performance. Death is the result of this disease, in children. With Tay-Sachs disease, the brain cells of a baby are unable to metabolize gangliosides, a type of lipid, because a crucial enzyme does not work properly. As the lipids accumulate in the brain, the brain cells gradually cease to function normally. Only children who inherit two copies of the Tay-Sachs allele qualifies as a recessive. At the biochemical level, we observe an intermediate phenotype characteristic of incomplete dominance: The enzyme deficiency that causes Tay Sachs disease can be detected in heterozygotes, who have an activity level of the lipid-metabolizing enzyme that is intermediate between individuals homozygous for the normal allele and individuals with Tay-Sachs disease. Heterozygotes lack symptoms of the disease, apparently because half the normal amount of functional enzyme is sufficient to prevent lipid accumulation in the brain. In fact, heterozygous individuals produce equal numbers of normal and dysfunctional enzyme molecules. At the molecular level, the normal allele and the Tay-Sachs allele are codominant. Sickle-cell disease is caused by the substitution of a single amino acid in the hemoglobin protein of red blood cells. When the oxygen content of an affected individual’s blood is low, the sickle-cell hemoglobin deforms the red cells to a sickle shape. Sickling of the cells, in turn, can lead to other symptoms. The multiple effects of a double dose of the sickle-cell allele exemplify pleiotropy, which is the ability of a gene to affect an organism in many ways. Regular blood transfusions could be used to ward off brain damage in children with sickle-cell disease. Heterozygotes with the sickle-cell allele may suffer some symptoms of the disease when there is a reduction of blood oxygen. Since the two alleles are codominant at the molecular level; both normal and abnormal hemoglobins are made. Only individuals who are homozygous for the sickle-cell allele suffer from the disease. Down syndrome 2000-03-24T13:00:00-04:00 http://75.150.148.189/free-essay/Genetic-Disorders-1793.aspx Nature vs. Nurture Controversy There is a big controversy between whether inherited genes or the environment influences and effects our personality, development, behavior, intelligence and ability. This controversy is most often recognized as the nature verses nurture conflict. Some people believe that it is strictly genes that effect our ways of life, others believe that it is the environment that effects us, and some believe that both of these influence us. Either way, social scientists have been struggling for centuries deciding whether our personalities are born or made. Tests are done often on identical twins that were separated to see how they are influenced. In the past twenty years, it has been discovered that there is a genetic component to about every human trait and behavior. However, genetic influence on traits and behavior is partial because genetics account on average for half of the variation of most traits. Urie Bronfrenbrenner, who studies genetics, said, "It is not nature vs. nurture, but the interaction of nature and nurture that drives development." Researchers are finding that the balance between genetic and environmental influences for certain traits change as people get older. Also, people may react to us in a certain way because of a genetically influenced personality and, we may choose certain experiences because they fit best with our instinctive preferences. This means that our experiences may be influenced by our genetic tendencies. One way researchers study the development of traits and behaviors is by measuring the influence of genetics through out ones life span, and it is found to be that the genetic influence on certain trait increase as people age. A research was done to see whether a trait would show up in a child if it was environmentally influenced or genetically influenced. A child was given more negative attention than another was, and it increased the chances of the child having depressive symptoms and anti-social behavior. But these symptoms disappeared when accounted for genetic influences and how parents treat their children. There are three types of gene/environment relations. The first one is called a passive correlation. It is to be explained as, for example, if a musical ability was genetic, and a child was passed a musical ability trait, than the child would most likely have musically inclined parents. Their parents then would provide them with the genes and environment to promote the development of that ability. The second one is called evocative. 2000-03-06T13:00:00-05:00 http://75.150.148.189/free-essay/Nature-vs_-Nurture-Controversy-1727.aspx Metabolism: Effect of Temperature on edno and ectotherms Animal metabolism consists of the utilization of nutrients absorbed from the digestive tract and their catabolism as fuel for energy or their conversion into substances of the body. Metabolism is a continuous process because the molecules and even most cells of the body have brief lifetimes and are constantly replaced, while tissue as a whole maintains its characteristic structure. This constant rebuilding process without a net change in the amount of a cell constituent is known as dynamic equilibrium (Grolier1996). In the combustion of food, oxygen is used and carbon dioxide is given off. The rate of oxygen consumption indicates the energy expenditure of an organism, or its metabolic rate (Grolier1996). Metabolic rate is directly linked to the core temperature in an animal. An ectotherm, or cold blooded animal, warms its body mainly by absorbing heat from its surroundings. The amount of heat it derives from its metabolism is negligible. In contrast, endotherms derive most or all of its body heat from its own metabolism (Campbells,p899). Because ectotherms do not produce their own heat, they cannot actively ensure their ideal temperature for an ideal metabolic rate (aquacult.htp). In the following experiment, we will attempt to examine the relationship between metabolic rate and environmental temperature in both an ectoderm and an endotherm. I predict that for the ectotherm, the metabolic rate will increase as the outside environment temperature will increase. I also predict that the metabolic rate in the endotherm will remain relatively the same as the outside environment temperature changes. I also make the prediction that the ectotherm will have much lower metabolic rates than the endotherm. The procedures for this experiment are those that are referred to in Duncan and Townsend, 1996 p9-7. In our experiment however, each student group chose a temperature of either 5 C, 10 C, 15 C, or 20 C. Each group selected a crayfish, and placed it in an erlenmeyer flask filled with distilled water. The flask’s O2 levels had already been measured. the flask was then placed in a water bath of the selected temperature for thirty minutes, and then the O2 levels were measured again. Each group shared their findings with the class. The metabolic rates of the mouse were conducted by the instructor and distributed. We also did not use the Winkler method to measure the O2 levels. We used a measuring device instead. The results of this experiment are shown in the 2000-03-01T13:00:00-05:00 http://75.150.148.189/free-essay/Metabolism-Effect-of-Temperature-on-edno-and-ectotherms-1713.aspx Heart Attacks A heart attack occurs when the blood supply to a portion of the heart muscle is severely reduced or stopped. This happens when one of the arteries that supply blood to the heart muscle is blocked by an obstruction. This blockage can be due to a condition called atherosclerosis (a build up of fatty like substance along the wall of the artery), a blood clot or a coronary vessel spasm along with a total obstruction. If the blood supply to a portion of the heart stops, that area of the heart will no longer receive the oxygen or nutrients needed to carry out its function and will die. If it is a very small part of the heart involved, it will be able to work without it. If a large portion is damaged, irreversible damage will happen which can lead to death. Damage to the heart muscle may be so severe that it may cause abnormal heart rhythm, called arrhythmias. Most people who are of a myocardial infraction or a heart attack do so within a few hours due to a type of arrhythmia The heart attack victim will complain of pressure, discomfort or a squeezing sensation in the centre of the chest. There may be pain radiating to the arms or the neck. There may also be shortness of breath, weakness, fatigue, nausea, vomiting and or indigestion. The pain that occurs is the result of heart tissue ischemia (decreased blood supply). The area that is not receiving enough blood is literally crying out for help. When a person complains of any of the symptoms mentioned, they should be transported to the nearest hospital. The diagnosis of an M.I. is made for the patient's history, from special tests on E.C.G. and measurement of certain enzymes released into the bloodstream from damaged heart muscle. Once an M.I. has occurred and a portion of the heart muscle has died, something has to be done to prevent a piece of the obstruction from breaking off and blocking another artery somewhere else in the body. There are four main techniques to prevent this. Drugs may be given to breakdown a blood clot. The obstruction can be cleared by pushing the plaque towards the wall of the artery by inflating a balloon inside the artery (balloon angioplasty). The obstruction can be loosened up by brushing it and suctioning it out of the artery, this is called atheroectomy. 2000-02-22T13:00:00-05:00 http://75.150.148.189/free-essay/Heart-Attacks-1673.aspx The Male Sexual Anatomy In Greek art, the male human nude was used as a canon of human perfection. The sensuous male form in motion was considered the crowning achievement of Greek sculpture. Its asymmetrical balance, this motion while at rest, and the resulting harmony of opposites is the essence of male beauty. The following will discuss the male sexual anatomy, physiology, and overall sexual health. In examining the male sexual body, the anatomy encompasses both the external and the internal sex organs. The external sex organs consist of the penis and the scrotum. The internal sex organs consist of the testes, genital ducts, and the fluid producing glands. The systems of internal and external organs that are the male genitals are also referred to as the urogenital system. The penis is the male organ that is responsible for the transmission of urine and semen from the body. It is an expanding flexible rod which, splits into an Y and is attached to the underside of the pubic bone. It consists of fibrous tissue, nerves, blood vessels, and three cylinders of erectile tissue. This tissue soaks up blood and expands when the brain signals certain arteries to begin pumping blood through, which produces an erection. The purpose of an erection in the reproductive process is to allow the penis to become firm enough to enter a vagina. The scrotum is a loose sac of skin, fascia, and smooth muscle that encloses and supports the testes outside the body at an optimum temperature for the production of sperm. The scrotum is divided into two parts with each containing a testis. The testes produce sperm and the sex hormone testosterone. "In most men the left testis hangs somewhat lower than the right one, although the opposite may sometimes occur." (Byer 153) The epididymis is a coiled tube about 20ft long, which runs along the posterior side of the testis. It stores sperm and can retain them for up to six weeks, during which time the sperm become mature. The viability of the sperm in the testes is dependent upon the relative lower temperature of the testes in comparision to the body temperature. When the environmental temperature is low the testes move closer to the body by way of the spermatic cord and relaxes when the temperature is too high and moves away from the body. The spermatic cord is covered with skeletal muscle and it suspends the testes 2000-01-09T13:00:00-05:00 http://75.150.148.189/free-essay/The-Male-Sexual-Anatomy-1570.aspx Cystic Fibrosis About 1 out of 201 Caucasian people carries at least one of the fatal defective genes that cause cystic fibrosis, CF, or mucoviscidosis (in Europe) although carriers don't show any signs of the disease. Therefore, 10 million2 people carry the defective gene and aren't aware of it. Consequently, it makes it one of the most common genetic defect in the United States. CF is a autosomal recessive gene. That means that it may, but doesn't always skip generations. In order to get this disease, both parents must be carriers. If one parent has CF and the other one is not a carrier than there is a 100% chance that their child will be a carrier. If one parent has CF and the other is a carrier than the child has a 50% chance of having CF and a 50% chance of just being a carrier. If both parents are carriers than their child will have a 25% of having CF, a 50% chance of being a carrier and a 25% chance of not being affected. CF is common in both males and females, there is not a specific sex that it is more common in. How does a person know if they have CF? There are many symptoms to this deadly disease including: salty tasting skin, constant coughing, large amounts of mucus, trouble gaining weight, frequent greasy, foul smelling bowel, growths in the nose (nasal polyps) and clubbed or enlarged fingertips and toe tips is another symptom. Now there are many tests that can be done to find put if a person has CF. One way which CF can be detected is to observe the symptoms. A person doesn't need to have all the symptoms in order to have cystic fibrosis, but they usually show most of them. Another way are different genetic testing. Doctors can now do genetic testing for CF, but about 10 years ago they couldn't. In 1989, the location where the of the defective gene on chromosome number 7 is was discovered by Francis S. Collins from University of Michigan. Tests can now be taken to see if an unborn child is infected with CF such tests are amniocentesis, chronic villus biopsy3 and a removal of cells from the embryo during invitro. Many years ago, New York4 had a heat wave, 1999-12-30T13:00:00-05:00 http://75.150.148.189/free-essay/Cystic-Fibrosis-1538.aspx Sleep Apnea Sleep apnea is a common sleeping disorder where a person has experiences of not breathing during sleep. Over 20 million Americans, mostly overweight men, suffer from sleep apnea. Despite these numbers, sleep apnea is often not treated directly because its symptoms are thought to be those of depression, stress, or just loud snoring. There may be a genetic component to this disorder as it often occurs within families. People with sleep apnea stop breathing for at least 10 seconds at a time; these short stops in breathing can happen up to 400 times every night. The Greek word "apnea" literally means "without breath". There are three types of apnea: obstructive, central, and mixed. Obstructive sleep apnea is the most common type. Nine out of 10 patients with sleep apnea have this kind of apnea. If you have this type, something is blocking the passage or windpipe, called the trachea, that brings air into your body. Your windpipe might be blocked by your tongue, tonsils, or uvula. It might also be blocked by a large amount of fatty tissue in the throat or even by relaxed throat muscles. Central sleep apnea is rare. This type is called central because it is related to the function of the central nervous system. If you have this type of apnea, the muscles you use in breathing don't get the "go ahead" signal from your brain. Either the brain doesn't send the signal, or the signal gets interrrupted. Mixed sleep apnea, as the name implies, is a combination of the two. So, what are the signs? One example is when a person sleeps, they have a very pronounced snore-- more like a loud and sudden snort. This "gasp for air" is literally a life saver when the mouth and throat muscles tense up to allow air back into the body. Most sleepers are unaware of this occurrence, although it often shakes their bed partners, roommates, and even neighbors to the core. Another sign is when a person falls asleep at inappropriate times like work, driving, sitting in a chair, or in front of a television. It can also be a sign of sleep apnea if a person frequently has morning headaches, memory difficulties, low energy levels, agitation, shortness of breath, or leg swelling. These are the main symptoms seen when 1999-12-13T13:00:00-05:00 http://75.150.148.189/free-essay/Sleep-Apnea-1460.aspx Cloning Bioethics, which is the study of value judgments pertaining to human conduct in the area of biology and includes those related to the practice of medicine, has been an important aspect of all areas in the scientific field (Bernstein, Maurice, M.D.). It is one of the factors that says whether or not certain scientific research can go on, and if it can, under which rules and regulations it must abide by. One of the most recent and controversial issues facing our society today is the idea of cloning. On February 23, 1997, Ian Wilmut, a Scottish scientist, along with his colleagues at the Roslin Institute and PPL Therapeutics, announced to the world that they had cloned a lamb, which they named Dolly, after Dolly Parton, from an adult sheep (Mario,Christopher). The two share the same nucleic DNA, but differ in terms of their mitochondrial DNA, which is vitally important for the regulation of the cell. The media and the press ignored this fact, and thus claimed that Dolly and her ‘mother’ were genetically identical, which sparked a fury of outcry all around the world. The technique of transferring a nucleus from a somatic cell into an egg cell of which the nucleus had been removed, called nuclear transplantation, is an extension of research that had been ongoing for over 40 years. Up until now, scientists thought that adult cells could not be “reprogrammed” to behave like a fertilized egg and create an embryo, but the evidence obtained by Dolly’s success prove otherwise. The issues of cloning have been around for a long time, starting with the publication of Joshua Lederberg’s 1966 article on cloning in the American Naturalist. The public’s interest has been perked by many sci-fi books, films, and movies including Aldous Huxley’s 1932 novel “Brave New World,” 1973’s “Sleeper,” the 1978 film “The Boys from Brazil”. Most recently, the movie “Multiplicity” dealt with replicating Billy Crystal over and over (Mario, Christopher). The ethical, legal, and moral issues aroused by cloning have been raised by previous projects, and are now simply emerging again, with its focus on three major points: the shift from sexual reproduction with that of asexual replication of existing genes; the ability to predetermine the genes of a child; and the ability to create many genetically identical children (Report/Recommendations of the NBAC). The public responded to Dolly with a mixture of fear and excitement, questioning the benefits 1999-11-27T13:00:00-05:00 http://75.150.148.189/free-essay/Cloning-1363.aspx Evolution We act like animals, we eat like animals, and we are animals. The many theories of evolution such as Darwin's theory of evolution prove to us that we choose to believe that we are not animals when we really are. Evolution is the sequencial process of change over periods of time, which shapes and establishes the formation of modern man. In referring to evolution, the word means various changes. Evolution refers to the fabrication and development of life on earth. "Organic evolution" is the concept that all living beings evolved from simple organisms and have changed throughout the periods of time to create many and various types of species. Organic evolution is better known as the "theory of evolution." There are three main theories of evolution, which are, the early theories proposed by Comte de Buffon, Baron Cuvier, and Lamarck, the synthetic theory, and the Darwin theory. In the 1700s, French naturalists, Comte de Buffon and Baron Cuvier concluded with the studies of fossils and comparative anatomy that life on earth had endured many changes through a long period of time. In the early 1800s, another French naturalist named Lamark, proposed the first complete theory of evolution. He observed through is observations, depending on the extent to which the use of the structure, that an animal's body structure is able to change during its life span. He also noted that organs and muscles, which were used often, tended to become larger and stronger. On the contrary, the organs and muscles, which were used seldom, tended to become smaller and diminish. With these observations, Lamarck concluded that these characteristics were hereditary. Proposed during two decades, the 1930s and 1940s, the synthetic theory involved a group of scientists. The group of scientists included two American biologists, Russian Theodosius and German Ernst Mayr, and the British geneticist and statistician Ronald A. Fisher. Together, they proposed the synthetic theory which combined Darwin's theory of natural selection with the ideals of genetics. In 1808, French naturalist Chevalier de Lamarck contemplated a theory of evolution, although, his theory of evolution did not gain any recognition until 1858. In 1858, British naturalist Charles R. Darwin furnished his theory of evolution, also known as Darwin's theory. Along with Darwin's theory of evolution there early theories and the synthetic theory. In 1858, Charles Darwin furnished his theory of evolution and the majority of scientists accept the Darwin theory today. The 1999-11-10T13:00:00-05:00 http://75.150.148.189/free-essay/Evolution-1143.aspx The Human Eye The Eye is the organ of sight. Eyes enable people to perform daily tasks and to learn about the world that surrounds them. Sight, or vision, is a rapidly occurring process that involves continuous interaction between the eye, the nervous system, and the brain. When someone looks at an object, what he/she is really seeing is the light that the object reflects, or gives off. This reflected light passes through the lens and falls on to the retina of the eye. Here, the light induces nerve impulses that travel through the optic nerve to the brain, where it makes an image of the object, and then that image is passed on to muscles and glands. The eye is well protected. It lies within a bony socket of the skull. The eyelids guard it in front. They blink an average of once every six seconds. This washes the eye with the salty secretion from the tear, or lachrymal, glands. Each tear gland is about the size and shape of an almond. These glands are located behind the upper eyelid at the outer corner of the eye. After passing over the eye, the liquid from the gland is drained into the nose through the tear duct at the inner corner of the eye. Heavy laughter or crying causes muscles in the upper eyelid to squeeze the lachrymal gland. This produces tears that flow too fast to be drained away. The eyelashes catch many flying particles that otherwise would enter the eye. As further protection, the eyelids automatically close when an object suddenly moves close to the eye. <b>Parts Of the Eye</b> The eye is made of 3 coats, or tunics. The outermost coat consists of the cornea and the sclera. The middle coat contains the main blood supply to the eye and consists of the choroid, the ciliary body, and the Iris. The innermost layer is the retina. <b>Cornea and Sclera</b> The Sclera, or the white of the eye, is composed of tough fibrous tissue. On the exposed area of the eye the scleral surface is covered with a mucous membrane called the conjunctiva. This protects the eye from becoming dry. The Cornea, a part of the sclera, is the transparent window of the eye through which light passes. The focusing of the light begins in the cornea. Behind the Cornea is a watery fluid called the aqueous humor. This fluid fills a curved, crescent shaped space, thick in the 1999-11-04T13:00:00-04:00 http://75.150.148.189/free-essay/The-Human-Eye-1118.aspx Erectyle disfunction Will we ever be able to produce something capable of making us reach the optimum of one of humankind's most basic needs? Will there always be a side effect? Since the beginnings of civilization, people have been obsessed about their sexuality. Men and women have always tried to achieve a maximum amount of pleasure in any possible way. For human beings this is obtained through the orgasm. Humans usually attain this is goal through sexual intercourse or masturbation. However, sometimes the psychological and physical conditions of a person can deprive him or her from reaching that goal. Thankfully, science and anatomy have also always interested mankind. This has helped to find solutions for problems dealing with our sexuality, which, as a matter of fact are very common. The most recurrent and drastic of all these dilemmas is that of impotence. The term "impotence" has traditionally been used to signify the inability of the male to attain and maintain erection of the penis sufficient to permit satisfactory sexual intercourse. However, this use has often led to confusing and uninterpretable results in both clinical and basic science investigations. This, together with its pejorative implications, suggests that the more precise term "erectile dysfunction" be used instead to signify an inability of the male to achieve an erect penis as part of the overall multifaceted process of male sexual function. Erectile dysfunction affects millions of men. Although for some men erectile function may not be the best or most important measure of sexual satisfaction, for many men erectile dysfunction creates mental stress that affects their interactions with family and associates. All these things might be very interesting, but to fully understand erectile dysfunction we must first take a look into the physiology of the male erection. In its most common form, the male erectile response is initiated by a central nervous system event that integrates psychogenic stimuli (perception, desire, etc.) and controls the sympathetic and parasympathetic innervation of the penis. Parasympathetic input allows an erection by relaxation of trabecular smooth muscle and dilation of the helicine arteries of the penis. This fills the spongy tissue that forms the penis with blood; a process referred to as the corporal veno occlusive mechanism. The erectile tissues must have sufficient stiffness to compress the blood vessels penetrating it so that venous outflow is blocked and sufficient tumescence and rigidity can occur. Constriction of the trabecular smooth muscle and helicine arteries 1999-10-02T14:00:00-04:00 http://75.150.148.189/free-essay/Erectyle-disfunction-1032.aspx Dandelion Information <b>Scientific name</b> -Kingdom-Plantea, Phylum- Tracheophyta, Class- Angiospermae, Order- Asterales, Family- Asteraceca, Genus- Taraxacum, Species- officiale <b>Description</b> - The Taraxacum officiale is a perennial herb that grows from two to eighteen inches tall they are a stem less plant 1999-04-08T14:00:00-04:00 http://75.150.148.189/free-essay/Dandelion-Information-644.aspx Nostoc Information <b>Scientific name</b> - Kingdom- Monera, Phylum- Cyanobacteria, Class- N\A, Order- nostocaler, Family- Nostocaceae, Genus- Nostoc, Species- caeruleum <b>Description</b>- Nostoc is a one celled autotrophic organism that performs 1999-04-08T14:00:00-04:00 http://75.150.148.189/free-essay/Nostoc-Information-645.aspx Yeast Information <b>Scientific name</b> -Kingdom- Fungi, Phylum- Ascomycota Class- Ascomycetes Order- Saccharomycetaler, Family- Saccharomycetaceae, Genus- Saccharomyces, Species- Cervisiae <b>Description</b> - Yeast is a unicellular organism that lacks chloroplasts. They are so small that it can't be seen by the naked eye and they are so small that it would take 4000 of them lined up side by side to measure an inch. <b>Habitat</b> - Yeast lives on and is nourished by dead or 1999-04-08T14:00:00-04:00 http://75.150.148.189/free-essay/Yeast-Information-646.aspx Do Men have Symptoms of PMS? The meaning of premenstrual, according to <a href="http://click.linksynergy.com/fs-bin/stat?id=pcZ8g7DjAzA&offerid=6424&type=2&subid=0&url=http%253A//search.borders.com/fcgi-bin/db2www/search/search.d2w/Details%253F%2526mediaType%253DBook%2526prodID%253D3805147" >Webster's Dictionary<IMG border=0 alt=icon width=1 height=1 src="http://ad.linksynergy.com/fs-bin/show?id=pcZ8g7DjAzA&bids=6424&type=2&subid=0" ></a>, is: "occurring before a menstrual period." Men do not have menstrual cycles, since they do not have uteri. A uterus is required for menses. Does the possibility exist that men have the symptoms of premenstrual syndrome (PMS)? Can the symptoms of premenstrual syndrome be associated with the male species? Due to the numerous symptoms associated with PMS, this essay deals with the symptoms of: irritability and stress, food cravings and weight gain, headaches . Just mentioing PMS makes some people irritable. How people express their irritability differs from each person. Some people express their irritable mood with body language. Such as, when a person throws his or her hands up in the air, and says, "touch me and die," this is a good indication that they are irritable. Most people's personalities control how they react to anger. Most people's personalities differ. Some people feel hostile, while others just show hostility. Most men say, "that they are just stressed out." Most men think that when women get stressed out, it is due to a hormone-imbalance due to PMS. Some people get food cravings when their hormones are imbalanced. Hormones control when people feel get cravings. Most people crave certain foods. Whether, the chocolate melts in their hands, the toppings are piled on the pizza, or they feel the need to lick the inside of the potato chip bag; people get cravings. Cravings can influence a person's diet. Some people eat healthy foods and exercise. They control their craving and eating habits. Other people give in to their bodies natural cravings. Some men use the excuse that they have a "sweet tooth" when they have a craving. But, most men say that when some women eat "they are stuffing their mouths." If a person does not exercise enough, and gives into too many cravings, they can get overweight. With ninety percent of the American adult population overweight; a lot of people are giving in to their cravings. Some people substitute food for affection. Others eat just because they are bored. Some people eat when they get depressed. Most people get depressed at some point in their lives. Hormone-imbalances can cause depression. Depression happens to some people when they have PMS. Hormones get released by certain hormone-producing glands into the body. The brain uses these hormones to dictate what 1999-04-02T14:00:00-04:00 http://75.150.148.189/free-essay/Do-Men-have-Symptoms-of-PMS-637.aspx Prolonged Preservation of the Heart Prior to Transplantation Picture this. A man is involved in a severe car crash in Florida which has left him brain-dead with no hope for any kind of recovery. The majority of his vital organs are still functional and the man has designated that his organs be donated to a needy person upon his untimely death. Meanwhile, upon checking with the donor registry board, it is discovered that the best match for receiving the heart of the Florida man is a male in Oregon who is in desperate need of a heart transplant. Without the transplant, the man will most certainly die within 48 hours. The second man's tissues match up perfectly with the brain-dead man's in Florida. This seems like an excellent opportunity for a heart transplant. However, a transplant is currently not a viable option for the Oregon man since he is separated by such a vast geographic distance from the organ. Scientists and doctors are currently only able to keep a donor heart viable for four hours before the tissues become irreversibly damaged. Because of this preservation restriction, the donor heart is ultimately given to someone whose tissues do not match up as well, so there is a greatly increased chance for rejection of the organ by the recipient. As far as the man in Oregon goes, he will probably not receive a donor heart before his own expires. Currently, when a heart is being prepared for transplantation, it is simply submerged in an isotonic saline ice bath in an attempt to stop all metabolic activity of that heart. This cold submersion technique is adequate for only four hours. However, if the heart is perfused with the proper media, it can remain viable for up to 24 hours. The technique of perfusion is based on intrinsically simple principles. What occurs is a physician carefully excises the heart from the donor. He then accurately trims the vessels of the heart so they can be easily attached to the perfusion apparatus. After trimming, a cannula is inserted into the superior vena cava. Through this cannula, the preservation media can be pumped in. What if this scenario were different? What if doctors were able to preserve the donor heart and keep it viable outside the body for up to 24 hours instead of only four hours? If this were possible, the heart in Florida could have been transported across the country to Oregon where the 1999-01-22T13:00:00-05:00 http://75.150.148.189/free-essay/Prolonged-Preservation-of-the-Heart-Prior-to-Transplantation-441.aspx Asthma Asthma is a condition of the bronchial tubes characterized by episodes of constriction and increased mucous production. A person with asthma has bronchial tubes that are super sensitive to various stimuli, or triggers, that can produce asthma symptom. In other words, asthmatics have special sensitivity that causes their lung tissue to react far more than is should to various stimulating factors or triggers. For this reason, people with asthma are said to have "twitchy airways." Some symptoms that people with asthma commonly experience are chest tightenings, difficulty inhaling and exhaling, wheezing, production of large amounts of mucous in their windpipes and coughing. Coughing can be frequent or intermittent, and can be loose-reflecting extra mucous secretion in the airways or dry and deep-reflecting tight bronchospasms. Not all these symptoms occur in every case of asthma. Sometimes people may have coughing without and symptoms for months or even years before it's realized that they are asthmatic. Interestingly enough, asthma symptoms are most severe at night, while we're lying down our airways narrow as a result of gravity changes. Also our lungs do not clear secretions as well at night, which leads to mucous retention, and that can increase the obstruction to air flow. Furthermore, at night our bodies produce smaller amounts of certain chemical that help to decrease airway spasms and keep airway tubes open. All of these factors add up to a greater chance of symptoms worsening at night. An asthma attack begins when the smooth muscles in the walls of the bronchial tubes start to tighten and narrow when they are exposed to a trigger when this bronchospasm occurs, air can't flow into or out of the lungs. To make matters worse, mucous enters the narrowed bronchial tubes and plugs them up, causing a further decrease in air flow. The bronchial tubes seem to close down, and air moving through these narrowed breathing passages can cause wheezing which is a high-pithched-whistlelike sound. Wheezing can be loud enough to be heard across a room, or it can be so slight that is takes a stethoscope to hear it. Airflow obstructions leads to air trapping in lungs. Once trapped, stale air builds up in the lungs. Asthma attacks can be so mild they're hardly noticed or so severe that asthmatics can feel like they're suffocating. Although more attacks seem to occur at night, they can virtually happen anytime. Attacks may come on very suddenly, or they may develop 1999-01-22T13:00:00-05:00 http://75.150.148.189/free-essay/Asthma-442.aspx The Importance Of Animal Research Research on animals is important in understanding diseases and developing ways to prevent them. The polio vaccine, kidney transplants, and heart surgery techniques have all been developed with the help of animal research. Through increased efforts by the scientific community, effective treatments for diabetes, diphtheria, and other diseases have been developed with animal testing. Animal research has brought a dramatic progress into medicine. With the help of animal research, smallpox has been wiped out worldwide. Micro-surgery to reattach hearts, lungs, and other transplants are all possible because of animal research. Since the turn of the century, animal research has helped increase our life-span by nearly 28 years. And now, animal research is leading to dramatic progress against AIDS and Alzheimer's disease. Working with animals in research is necessary. Scientists need to test medical treatments for effectiveness and test new drugs for safety before beginning human testing. Small animals, usually rats, are used to determine the possible side effects of new drugs. After animal tests have proven the safety of new drugs, patients asked to participate in further studies can be assured that they may fare better, and will not do worse than if they were given standard treatment or no treatment. New surgical techniques first must be carefully developed and tested in living, breathing, whole organ systems with pulmonary and circulatory systems much like ours. The doctors who perform today's delicate cardiac, ear, eye, pulmonary and brain surgeries, as well as doctors in training, must develop the necessary skills before patients' lives are entrusted to their care. Neither computer models, cell cultures, nor artificial substances can simulate flesh, muscle, blood, and organs like the ones in live animals. There is no alternative to animal research. Living systems are complex. The nervous system, blood and brain chemistry, and gland secretions are all interrelated. It is impossible to explore, explain or predict the course of many diseases or the effects of many treatments without observing and testing the entire living system. Cell and tissue cultures, often suggested as "alternatives" to using animals, have been used in medical research for many years. But these are only isolated tests. And isolated tests will yield only isolated results, which may bear little relation to a whole living system. Scientists do not yet know enough about living systems or diseases, nor does the technology exist, to replicate one on a computer. The information required to build a true computer 1999-01-22T13:00:00-05:00 http://75.150.148.189/free-essay/The-Importance-Of-Animal-Research-443.aspx The Effects Of Altitude On Human Physiology Changes in altitude have a profound effect on the human body. The body attempts to maintain a state of homeostasis or balance to ensure the optimal operating environment for its complex chemical systems. Any change from this homeostasis is a change away from the optimal operating environment. The body attempts to correct this imbalance. One such imbalance is the effect of increasing altitude on the body's ability to provide adequate oxygen to be utilized in cellular respiration. With an increase in elevation, a typical occurrence when climbing mountains, the body is forced to respond in various ways to the changes in external environment. Foremost of these changes is the diminished ability to obtain oxygen from the atmosphere. If the adaptive responses to this stressor are inadequate the performance of body systems may decline dramatically. If prolonged the results can be serious or even fatal. In looking at the effect of altitude on body functioning we first must understand what occurs in the external environment at higher elevations and then observe the important changes that occur in the internal environment of the body in response. <b>HIGH ALTITUDE</b> In discussing altitude change and its effect on the body mountaineers generally define altitude according to the scale of high (8,000 - 12,000 feet), very high (12,000 - 18,000 feet), and extremely high (18,000+ feet), (Hubble, 1995). A common misperception of the change in external environment with increased altitude is that there is decreased oxygen. This is not correct as the concentration of oxygen at sea level is about 21% and stays relatively unchanged until over 50,000 feet (Johnson, 1988). What is really happening is that the atmospheric pressure is decreasing and subsequently the amount of oxygen available in a single breath of air is significantly less. At sea level the barometric pressure averages 760 mmHg while at 12,000 feet it is only 483 mmHg. This decrease in total atmospheric pressure means that there are 40% fewer oxygen molecules per breath at this altitude compared to sea level (Princeton, 1995). <b>HUMAN RESPIRATORY SYSTEM</b> The human respiratory system is responsible for bringing oxygen into the body and transferring it to the cells where it can be utilized for cellular activities. It also removes carbon dioxide from the body. The respiratory system draws air initially either through the mouth or nasal passages. Both of these passages join behind the hard palate to form the pharynx. At the base of the pharynx 1999-01-22T13:00:00-05:00 http://75.150.148.189/free-essay/The-Effects-Of-Altitude-On-Human-Physiology-444.aspx Aggression In Man There are different reasons why a person may act aggressively towards other human beings. The person may act this way because of his culture or the way he was brought up in society. The person does not, however, act this way based on instinct alone. Aggression is a molded, learned behavior. A human being must have both environmental and instinctual factors in order to display aggression. Some of a person's natural instincts are to desire food, reject certain things, escape from danger, fight when challenged, sex desire, care for the young, dominate, and to accept inferior status. The combination of instincts and environment determines a person's behavior. This is based on the theory that everything human beings do would have to be learned from other human beings. Aggression must be learned; it is not simply there from birth. Rather than being an uncontrollable instinct, a person's behavior is something that is taught to him. For example, a newborn baby is breathing because it is an involuntary reflex. On the other hand, a father may tell his young son to beat up the school bully who is picking on him. As a result, the boy is taught to deal with the situation by using violence. In order for an individual to display aggression, it must be driven by an instinct interacting with that person's surroundings. McDougall defines the word instinct as "an inherited or innate psycho-physical disposition which determines its possessor to perceive, and to pay attention to, objects of a certain class, to experience an emotional excitement of a particular quality upon perceiving such an object, and to act in regard to its particular manner, or, at least, to experience an impulse to such action." This definition basically explains that people have different reactions for different stimuli. Therefore, an individual is prone to act a certain way when he is stimulated to do so from his surrounding environment. For example, the Eskimo does not have an innate instinct that allows him to survive in his climate. He is taught to work with his people in order to survive when he is very young. When people are brought up in a society, they learn certain customs and traditions. These customs are usually taught to them because it's part of their society's way of life, even though some of the customs may seem cruel and repulsive to others. For example, cannibalism is abhorrent to 1999-01-22T13:00:00-05:00 http://75.150.148.189/free-essay/Aggression-In-Man-445.aspx Eukaryotic Organelles The mitochondria has an eggshape structure. The mitochondria consists of an inner and outer membrane. The outer membrane is what shapes the organelle to its egglike shape. The inner membrane which folds inward makes a set of "shelves" or cristae that allow the reactions of the mitochondria to take place. The more the mitochondria makes these reactions the more the inner membrane folds. This happens because the mitochondria now has more surface area connecting it to its surroundings. The 1999-01-22T13:00:00-05:00 http://75.150.148.189/free-essay/Eukaryotic-Organelles-447.aspx Diabeties There are two types of diabetes: diabetes insipidus and diabetes mellitus. Diabetes insipidus is a rare metabolic disorder caused by a deficiency of the pituitary hormone, which is usually the result of damage to the pituitary gland. Diabetes insipidus is characterized by enormous amounts of urine that are produced by the body regardless of how much liquid is consumed. Diabetes mellitus results from the production of insufficient amounts of insulin by the pancreas. Without insulin the body cannot utilize glucose, thus creating a high level of glucose in the blood and a low level of glucose absorption by the tissues. Diabetes mellitus is generally divided into two categories: type I called insulin-dependent or juvenile diabetes and type II in which the onset of the diabetes occurs during adulthood. The symptoms of the type I diabetic include irritability, frequent urination, abnormal thirst, nausea or vomiting, weakness, fatigue, and unusual hunger. This type of diabetes occurs mostly in children or young adults. The type I diabetic may have an insulin reaction in an instant, seeming perfectly normal one second and becoming unconscious the next. The early warning signs of this type of reaction are hunger, dizziness, sweating, confusion, palpitation, and numbness or tingling of the lips. If left untreated, the insulin-dependent diabetic may also experience double vision, trembling, and disorientation, may perform strange actions, and may eventually lose consciousness. While experiencing any one of these symptoms, quick consumption of a piece of candy, some soda pop, or anything else that contains sugar will bring blood sugar levels back to normal. Recovery is more difficult for the diabetic whose insulin reaction is left untreated for a long period of time. An insulin reaction producing low blood sugar can be life threatening. Therefore, it is safer to "spill" small amounts of urine sugar when taking insulin. The second type of diabetes, often referred to as maturity-onset diabetes, is likely to occur in those with a family history of diabetes and is characterized by blurred vision, itching, unusual thirst, drowsiness, obesity, fatigue, skin infections, slow healing, and tingling or numbness in the feet. Onset of symptoms is usually later in life. Diet often controls this type and insulin is not usually required. Obesity is a major factor in type II diabetes. An estimated 5.5 million Americans are being treated for diabetes. Studies indicate that there are 5 million adults with undetected type II diabetes, and another 20 million have 1999-01-22T13:00:00-05:00 http://75.150.148.189/free-essay/Diabeties-448.aspx The End Permian Mass Extinction <b>Introduction</b> Think of a world which existed 290 million years ago. As you look out over the terane in front of you, you think that you are on an alien planet. You see volcanoes spewing ash and lava. Beside them is the ocean which is swarming with many different species of echinoderms, bryozoans and brachiopods. As you look down onto the sea floor you are amazed at the countless number of starfish and urchins. Some animals leave you can't even describe and you have no idea even what phylum they belong to. This is a world at its height in diversity of oceanic species. Millions of wonderous species existed at this time in the ocean and most of them will never appear again in earth's history. In the geologic time scale, a million years means nothing but this time things are different. In the blink of an eye things now look vastly different. The world once again looks alien but it looks worse than before. The sky is dark. Oceans are no longer teaming with life. The stench of rotting flesh and plants hangs in the air. The ground trembles under your feet. You feel an intense heat burning you face. You look up and see one of the greatest show of force mother nature has ever shown. Whole mountains are being thrown in the air. Lava and debris are everywhere. You ask yourself, what has happened? Will life ever exist on earth again? The above paragraph is a primative example of what the end of the Permian period could have looked like. Marine life was devastated, with a 57% reduction in the number of families (Sepkoski, 1986) and an estimated 96% extinction at the species level (Raup, 1979). Oceanic life suffered the most but terrestrial life forms were also greatly affected. There was a 77% reduction in the number of tetrapod families (Maxwell and Benton, 1987). All major groups of oceanic organisms were affected with the crinozoans (98%), anthozoans (96%), brachiopods (80%) and bryozoans (79%) suffering the greatest extinction (McKinney, 1987). The end of the Permian and beginning of the Triassic periods marked the single greatest extinction event the world has ever faced. <b>Timing of the Extinction</b> There are many questions regarding the timing of the extinction at the end of the Permian. One of the main questions was the even a catastrophy or gradual. There is evidence for both senarios. Some of 1999-01-22T13:00:00-05:00 http://75.150.148.189/free-essay/The-End-Permian-Mass-Extinction-451.aspx Extracting DNA from the Bacterium Escherichia coli <b>Introduction</b> Deoxyribonucleic acid is contained in all cells. The structure of DNA makes gene transmission possible. Since genes are segments of DNA, DNA must be able to make exact copies of itself to enable the next generation of cells to receive the same genes. The DNA molecule looks like a twisted ladder. Each "side" is a chain of alternating phosphate and deoxyribose sugar molecules. The "steps" are formed by bonded pairs of purine-pyrimidine bases. DNA contains four such bases the purines adenine (A) and guanine (G) and the pyrimidines cytosine (c) and thymine (T). The RNA molecule, markedly similar to DNA, usually consists of a single chain. The RNA chain contains ribose sugars instead of deoxyribose. In RNA, the pyrimidine uracil (U) replaces the thymine of DNA. DNA and RNA are made up of basic units called nucleotides. In DNA, each of these is composed of a phosphate, a deoxyribose sugar, and either A, T, G, or C. RNA nucleotides consist of a phosphate, a ribose sugar, and either A, U, G, or C. Nucleotide chains in DNA wind around one another to form a complete twist, or gyre, every ten nucleotides along the molecule. The two chains are held fast by hydrogen bonds linking A to T and C to G A always pairs with T (or with U in RNA); C always pairs with G. Sequences of the paired bases are the foundation of the genetic code. Thus, a portion of a double-stranded DNA molecule might read: A-T C-G G-C T-A G-C C-G A-T. When "unzipped," the left strand would read: ACGTGCA; the right strand: TGCACGT. DNA is the "master molecule" of the cell. It directs the synthesis of RNA. When RNA is being transcribed, or copied, from an unzipped segment of DNA, RNA nucleotides temporarily pair their bases with those of the DNA strand. In the preceding example, the left hand portion of DNA would transcribe a strand of RNA with the base sequence: UGCACGU. <b>Genes and Protein Synthesis</b> A genetic code guides the assembly of proteins. The code ensures that each protein is built from the proper sequence of amino acids. Genes transmit their protein-building instructions by transcribing a special type of RNA called messenger RNA (mRNA). This leaves the cell nucleus and moves to structures in the cytoplasm called ribosomes, where protein synthesis takes place. Cell biologists believe that DNA also builds a type of RNA called transfer RNA, which 1999-01-22T13:00:00-05:00 http://75.150.148.189/free-essay/Extracting-DNA-from-the-Bacterium-Escherichia-coli-452.aspx Heart Disease <b>INTRODUCTION</b> In today's society, people are gaining medical knowledge at quite a fast pace. Treatments, cures, and vaccines for various diseases and disorders are being developed constantly, and yet, coronary heart disease remains the number one killer in the world. The media today concentrates intensely on drug and alcohol abuse, homicides, AIDS and so on. What a lot of people are not realizing is that coronary heart disease actually accounts for about 80% of all sudden deaths. In fact, the number of deaths from heart disease approximately equals to the number of deaths from cancer, accidents, chronic lung disease, pneumonia and influenza, and others, COMBINED. One of the symptoms of coronary heart disease is angina pectoris. Unfortunately, a lot of people do not take it seriously, and thus not realizing that it may lead to other complications, and even death. <b>THE HUMAN HEART</b> In order to understand angina, one must know about our own heart. The human heart is a powerful muscle in the body which is worked the hardest. A double pump system, the heart consists of two pumps side by side, which pump blood to all parts of the body. Its steady beating maintains the flow of blood through the body day and night, year after year, non-stop from birth until death. The heart is a hollow, muscular organ slightly bigger than a person's clenched fist. It is located in the centre of the chest, under the breastbone above the sternum, but it is slanted slightly to the left, giving people the impression that their heart is on the left side of their chest. The heart is divided into two halves, which are further divided into four chambers: the left atrium and ventricle, and the right atrium and ventricle. Each chamber on one side is separated from the other by a valve, and it is the closure of these valves that produce the "lubb-dubb" sound so familiar to us. (see Fig. 1 - The Structure of the Heart) Like any other organs in our body, the heart needs a supply of blood and oxygen, and coronary arteries supply them. There are two main coronary arteries, the left coronary artery, and the right coronary artery. They branch off the main artery of the body, the aorta. The right coronary artery circles the right side and goes to the back of the heart. The left coronary artery further divides into the left circumflex and the left anterior descending 1999-01-22T13:00:00-05:00 http://75.150.148.189/free-essay/Heart-Disease-457.aspx The Human Heart <b>Abstract:</b> Dorland's Illustrated Medical Dictionary defines the heart as "the viscus of cardiac muscle that maintains the circulation of the blood". It is divided into four cavities; two atria and two ventricles. The left atrium receives oxygenated blood from the lungs. From there the blood passes to the left ventricle, which forces it via the aorta, through the arteries to supply the tissues of the body. The right atrium receives the blood after it has passed through the tissues and has given up much of its oxygen. The blood then passes through the right ventricle into the lungs where it gets oxygenated. There are four major valves in the heart; the left atrioventricular valve (also known as the mitral or bicuspid valve), the right atrioventricular valve (tricuspid), aortic valve, and the pulmonary valve. The heart tissue itself is nourished by the blood in the coronary arteries.2 <b>Position of the Heart Within the Body:</b> The heart is placed obliquely in the chest. The two atria are directed upwards and backwards to the right and are at the level of the fifth through the eight dorsal vertebrae. The apex of the heart points downwards and forwards to the left and corresponds to the interspace between the fifth and sixth ribs, two inches below the left nipple. Its atrial border corresponds to a line drawn across the sternum on a level with the upper border of the third costal cartilage. Its lower border (apex) corresponds to a line drawn across the lower end of the same bone, near the xiphoid process. Its upper surface is rounded and convex, directed upwards and forwards, and formed mainly by the right ventricle and part of the left ventricle. The posterior surface of the heart is flattened and rests upon the diaphragm muscle. Of its two borders, the right is the longest and thinnest, the left is shorter but thicker and round. <b>Size:</b> In an adult, the heart measures about five inches in length, three and a half inches in the broadest part of its transverse diameter, and two and a half inches in its antero-posterior. The average weight in the male varies from ten to twelve ounces. In the female, the average weight is eight to ten ounces. The heart will continue to grow in size up to an advanced period of life. This growth is more obvious in men than in women.3 <b>Circulation of Blood in an Adult:</b> The heart is subdivided 1999-01-22T13:00:00-05:00 http://75.150.148.189/free-essay/The-Human-Heart-458.aspx