DNA

Deoxyribonucleic Acid - the fingerprint of life also know as DNA was first mapped out in the early 1950's by British biophysicist, Francis Harry Compton Crick and American biochemist James Dewey Watson. They determined the three-dimensional structure of DNA, the substance that passes on the genetic characteristics from one generation to the next. DNA is found in the chromosomes in the nucleus of a cell. "Every family line has it's own unique pattern of restriction-enzyme DNA fragments. This variation in patterns of DNA fragments found in human genetic lineages is called 'restriction-fragment length polymorphism'(RFLP). (Louis Levine, ?) Because each person, except for identical twins(which have the exact same DNA), is formed from two family lines the pattern of sizes of the fragments from an individual is unique and can serve as a DNA fingerprint of that person. These 'fingerprints' have became very important in identifying criminals in a number of violent crimes where the victims aren't able to. Blood or semen stains on clothing, sperm cells found in a vaginal swab taken after a rape, or root hairs are all available for analysis. Although other body tissues such as skin cells and saliva can provide genetic information about a person for Forensic Science purposes, blood is the most useful source of inherited traits. If the DNA fingerprints produced from two different samples match, the two samples pr obably came from the same person. Here are some examples of court cases where DNA plays an important roll in the outcome of the trial. ----Hauppauge N.Y.---After 11 years in prison for rape Kerry Kotler cried tears of joy becoming one of the first convicts in the United States to be freed by DNA technology. - 1 - At a banquet held for Kotler he received a standing ovation from the guest's of his lawyer, Barry Schech and Peter Neufeld, who would later use their DNA expertise to help free O.J. Simpson. Now the very weapon used to free Kotler will be used against him and instead of his lawyers praising DNA testing they will be trying to tear it down. Four years after being released from prison Kotler was charged with another rape and the DNA test matched him to the semen found on the victims clothing. Posing as a police officer he forced a 20 year old college student off the highway and raped her. A partial license plate number and a description of the car led them to Kotler. The semen matched Kotler's blood and the chances of the semen being somebody else's is one to 7.5 million. Also, dog hairs on the victims clothing matched hairs from Kotler's German shepherd. Kotler, 37, is free on $25000 bail and could get up to 50 years in jail if convicted of rape and kidnapping. ----Anamosa, Iowa---22 year old Cathy Jo Bohlken was sexually assaulted and murdered. Genetic evidence from fluid taken from her body points to an 18 year old named Travis Jamieson. Bohlkan's body was found DEC 26, 1993 on the floor of her duplex with a bag over her head and her hands wrapped with duct tape. Autopsy shows she died of multiple stab wounds. The search of a pick-up truck registered to Jamieson's parents revealed a utility knife and a "red-brown stain" on the steering wheel. (http://www.wcinet.com/th/news/th0208/stories/1355.htm) ----Norman, Okla---Thomas Webb III was released after more than 13 years in prison for a 1982 rape. DNA testing was not available at the time so Gale Webb, Thomas' wife, pushed - 2 - authorities to use DNA genetic profiling on the 14 year old evidence. These DNA tests ruled him out as a suspect. (http://www.wcinet.com/th/news/th0525/stories/12284.htm) ----Santa Ana, Calif---Kevin Lee Green cried as the judge apologized for the mistake and freed him from prison after nearly 17 years. He was convicted of killing his unborn baby and nearly beating his wife to death. He was released as authorities prepared to charge a convicted rapist with the murder of Green's unborn child. The reversal of Green's conviction came after another man confessed and his statement was backed up by DNA technology not available in 1980. He was sent to prison on the testimony of his wife who at first didn't remember the attack but that her memory suddenly returned as she read a baby magazine. She testified that her husband severely beat her because she refused sex. Green insisted that he left to get a cheeseburger and came home to see a man leaving in a van. Authorities now believe the attacker was Gerald Parker, 41, who owned a van at the time. He is suspected to be in the "bedroom basher" serial killings in Orange County in 1978 and 1979. (http://www.wcinet.com/th/news/th0622/stories/15897.htm) ----San Francisco---Theodore Kaczynski, 54, has been jailed in Helena, Mont. since his arrest April 3rd at the mountain cabin where he spent most of his time since quitting his job at the University of California in 1969. The former math professor has been charged with possession of bomb-making material. Kaczynski, the suspected Unabomber is blamed for 3 deaths and 23 injuries in an 18 year bombing spree that begun in 1978. DNA tests of saliva found on two letters-one sent by the Unabomber and one by Kaczynski to his family- - 3 - showed a genetic link. An FBI investigation found common phrases and misspellings between his writings and documents say were written by the Unabomber. A search of his cabin revealed the original copy of the Unabomber's 35000 word anti-technology manifesto, a typewriter used on the manifesto, bombs, bomb parts and detonators. (http://www.wcinet.com/th/news/th0615/stories/14962.htm) The accuracy of DNA fingerprinting has been challenged for many reasons. One reason is because DNA segments rather than complete DNA strands are fingerprinted, a DNA fingerprint may not be unique. There have been no large scale research to confirm the uniqueness of DNA fingerprints. Also, DNA fingerprinting is often done in private laboratories that may not follow uniform testing standards and quality controls, and since humans must interpret the test, human error could lead to false results. DNA fingerprinting is expensive, so suspects who are unable to provide their own DNA experts may not be able to adequately defend themselves against charges based on DNA evidence. There are two methods which can be used to test DNA. "The older one called 'restriction-fragment length polymorphism' (RFLP) takes up to two weeks to complete and requires a larger supply of high quality, uncontaminated DNA. The good thing about this test is that it finds the 'random repeats'. These extra chemical units give everyone's DNA a unique pattern. The newer method is called Polymerase Chain Reaction (PCR). This system uses an enzyme that can be directed towards regions of DNA known to contain variations. The results can be printed out in a series of blue dots. The good thing about this method is that it can be completed in a few days and it only requires a small amount of - 4 - DNA, even if it has begun to degrade and deteriorate. Although PCR is faster and easier it does have its drawbacks. The old method finds rarely repeated characteristics while PCR finds genetic features shared by many people. That means that the older method might show one person in a billion is likely to have the same DNA as a suspect while PCR shows that the same characteristics may be shared by as many as one in a thousand.(Nichols, P58) The discovery of DNA has led to tremendous advances in solving crimes but there is still a lot to learn. The technology of DNA is still in it's infancy and as it develops and as lab procedures become standardized DNA will be an even more powerful force in the courtroom.

Brain Transplant

Medical technology has seemed to advance enough so that doctors are able to perform brain transplants. So far this procedure has only been successfully performed on animals, and now doctors hope to perform this procedure on humans. I believe brain transplants should not be performed at all, and especially not on humans because of the numerous problems and side effects that could arise. Even though brain transplants can be successfully performed on animals, this does not mean that it will be successful with humans. The human brain is much more complex than the brain of animals, so there will be many more complications during surgery. For example, the healthy brain that was removed could have been damaged in some way without the doctors knowing it. It would also be very difficult to attach a person's brain in a different body because of the millions of neurons that send and receive messages to and from all over the body. It would be almost impossible to reconnect every single neuron, and without them a person could not function normally. Many psychological effects are also possible because the human brain is so complex. Our brain makes us who we are, and with a different brain we would no longer be unique. A person with a different brain would seem to be a total stranger and in many ways they would be. Hopefully these dangerous side effects will convince doctors not to perform this pr ocedure on humans. The advancement of technology can be very beneficial to everyone, but I do not believe that this medical technology of brain transplants will help anyone. We were all born with one brain and through childhood to adolescence our mind developed into who we are. No one should steal our identity from us, even if we are seriously injured, and change it to a completely new one. Also for the people who have died with healthy brains, that was their identity and it should not be given to anyone else. Another problem with brain transplants is how can doctors choose what are "healthy" or "normal" brains. An elderly person who has died would have an aged brain that would not be as efficient as a younger person's brain. Then would doctors have to find healthy brains of the same age as the person who needs it? This could also bring up other factors such as intelligence, gender, or physical problems that a person might have had before death. Also another problem might be with the period of time a brain can be kept "alive" after death and how it can be kept "alive" without damage. Overall, my feelings about this surgery are that it should not be done on humans until doctors have overcome all the problems and obstacles that stand in their way of making brain transplants with humans successful.

Body Systems

There are 10 body systems, one of them is the Integumentary (skin). It is composed of hair, skin, nails, sence receptions and oil glands. Its functionis to protect from outside, to regulate the body temperature, to make synthesis of hormones & chemicals and is used as a sense organ. Another one is the Skeletal System (bones). It is made of about 206 bones, that are divided in tho categories: axial bones (in the body by itself) and apendicular bones (arms & legs). We have Joints too. Thei`re divided in Ball Socket (like elbow and shoulders) and sattle (fingers). This system`s function are movement, storage of minerals, blood formation, support of the body and protection of body parts. The next one is the Muscular System. It is composed of muscles (dah). The muscles are divided in visceral or involuntary or smooth (The one in the organs, like intestines), skeletal or voluntary or striated (found superficial to the bones, like biceps, triceps...) and cardiac (heart). Their functions are movement, to maintain body posture & tone and in the production of body heat. Now its time for the Nervous System. Its constructed of the brain, the spinal cord and the nerves (neurons). Its functions are to communicate (fast with short duration), integration, and to control. The subsequent system is the Endocrine System (known as ductless too...). This is composed of a lot of things... They are:pituitary gland - below the brain (master gland), pineal gland - brain (It`s called the "third eye" by some, because its sensitive to light cycles), hypothalamus - also in the brain (it works with the pituitary), the thyrodic - neck (controls the metabolism), adrenal - kidneys (responsible for the adrenaline), pancreas - near stomach (produces insulin), ovaries - on females and testes - on males (it produces estrogen and ova - testosterone and sperm, respectively). Their functions are to secrete hormones into the blood, communication (slow & long duration), integration and control.

A Look at the Human Genome Project

Scientists are taking medical technology to new heights as they race to map all of the genes, nearly 100,000, in the 23 chromosomes of the human body. Along the way, they hope to understand the basis of, and maybe even develop methods of treating certain genetic diseases, such as Alzheimer's and Muscular Dystrophy. They plan to do this by identifying the DNA sequence of an abnormal gene in which a disease originates and comparing it with the data of a normal or healthy gene. The entire research project is entitled "The Human Genome Project." "The Human Genome Project" is a large scale project being conducted by more than 200 laboratories, with even more researchers and labs having joined in. Most of the labs and researchers are located in France and the United States. The project started in 1990 and was slated to take 15 years and cost $3 billion in U.S. money for the entire project coming to roughly $200 million per year. Federal funding for the project is nearly 60% of the annual need. This has created some funding problems for the project. There also have been technological advances and discoveries that have helped to speed up the project. This automation may help to reduce the cost and help the project to meet its objectives ahead of schedule. The project was estimated to have detailed maps of all of the chromosomes and know the location of most of the human Genes by 1996. Researchers have successfully located the gene and DNA sequence for Huntington's Disease on Chromosome 4 and have created a genetic test to determine if a person carries this gene. "The child of a person with Huntington's has a 50% chance of inheriting the gene, which inevitably leads to the disease." Once an individual acquires the gene, it is only a matter of time before they acquire the disease. Because the medical costs of treating such persons in terminal illnesses are extremely high, insurance companies who want to stay in business see this genetic test, and others like it, as an opportunity to screen prospective clients for the probability of such diseases. Some people feel that this information gives insurance companies unfair advantage over those covered by medical insurance and point out that release of genetic information to insurance companies puts a severe disadvantage on the person who is screened, as well as violates the patients right to privacy. If this genetic information is not safegua rded as confidential for the patient's and doctor's knowledge alone, then the patient can be labeled as undesirable and the patient may not be able to receive insurance coverage at any price. This also brings up other ethical questions. "Does genetic testing constitute an invasion of privacy, and would it stigmatize those found to have serious inborn deficiencies? Would prenatal testing lead to more abortions? Should anyone be tested before the age of consent?" Obviously, many genetic advancements are to come of this research. One biotechnology that will benefit from genetic testing is genetic engineering. It too, may have many social implications depending on what is created from such experimentation. Gene Therapy is one "spin-off" that has greatly benefited Gene-mapping. It utilizes genetic engineering to treat genetic disorders by "introducing genes into existing cells to prevent or cure diseases" . Most of the methods are still in the experimental stages and have yet to be approved by the FDA. One example would be in a proposed treatment for a brain tumor. Scientists would take a herpes gene and splice it in to a nonvirulent virus. Viruses and liposomes have an uncanny ability to navigate through cell membranes. The virus is then placed into a laboratory animal to reproduce itself, and after reproduction, is injected into the human's brain tumor. The virus is supposed to invade the tumor cells. Thus, the herpes enzyme will render the tumor vulnerable to drugs used to cure herpes, killing the tumor, the virus, and the animals' cells used to manufacture the virus. With this and other ideas springing out from the "medicine cabinet", many researchers are optimistic about the results of their research. There is also a direct correlation of the sequencing of genes and production of effective drugs on diseases which may have different strands of defective genes, such as Alzheimer's. Locating these genes would be crucial to synthesizing a product to affect that specific location in the gene. The director of the gene-therapy program at the University of Southern California, Dr. W. French Anderson states, "Twenty years from now, gene therapy will have revolutionized medicine. Virtually every disease will have it as one of its treatments." Such an impact on medicine would take much longer to occur with "hit and miss" tactics, rather than methodically mapping out the blueprint for the body. So whether we, as society, want to go forward in this research slowly, or with blazing speed, scientists will go forward and do what they set out to do. The fact that this research will benefit humanity is resounding, we just need to remember to handle our findings in such a manner that benefits all of society, not just those on top of the economical food chain. Also, persons should be able to decide for themselves if they can handle knowing what their genetic flaws are. Sometimes knowing you will eventually be afflicted by a disease can be as emotionally devastating as actually having the disease. Some states have already enacted laws guarding the rights of individuals genetically tested . The problem is that most only cover certain procedures and not all of the testing. Whatever way we govern such testing, we have to realize, will be inefficient by most standards, as government always is, in complicated situations. I feel that if genetic information should be public knowledge, then every country using this genetic concept should provide "blanket insurance" coverage for everyone at the same rate. This would be the only fair action that would have the common person's interest in mind, although it is a socialist concept, people would not be discriminated against and it would put everyone on a level playing field. Since I don't see a comprehensive health care plan in our horizon, we should consider making personal genetic information excluded from insurance companies, the government, etc., except for the actual treatment of the patient, which was the original reason that these tests were created. The reason that I feel genetic information should be totally excluded from insurance companies is this: Once genetic testing becomes widely available, it would be easy for an insurance company to require people to submit to a genetic test before they could be covered. If the person applying is found to be unfit, it could go on his or her insurance "medical report", such as a "credit report", which would blacklist that person from ever getting coverage. Obviously there is a need for governmental laws to prevent this from happening. No one can control what genes they will get, and just because you have "bad" genes doesn't mean you are a "bad" person, thus no one should be discriminated against due to these "weaknesses". I personally feel that the Human Genome Project is a great undertaking intended for the benefit of mankind. There are many advances that have been made in treatments as well as the creation of various machines that automate the process of gene mapping. Machines that may be used to automate th e study of other organisms. I just don't trust the motives behind the insurance companies who could unduly benefit from such testing. I feel that the individual's right to privacy should remain paramount, and that there should be laws set in motion to prohibit a person from being discriminated against because of genetic predisposition.

A Study of Inheritable Traits in Fruit Flies

The Drosophila melanogaster, more commonly known as the fruit fly, is a popular species used in genetic experiments. In fact, Thomas Hunt Morgan began using Drosophila in the early 1900's to study genes and their relation to certain chromosomes(Biology 263). Scientists have located over 500 genes on the four chromosomes in the fly. There are many advantages in using Drosophila for these types of studies. Drosophila melanogaster can lay hundreds of eggs after just one mating, and have a generation time of two weeks at 21°C(Genetics: Drosophila Crosses 9). Another reason for using fruit flies is that they mature rather quickly and don't require very much space. Drosophila melanogaster has a life cycle of four specific stages. The first stage is the egg, which is about .5mm long. In the 24 hours when the fly is in the egg stage, numerous cleavage nuclei form. Next, the egg hatches to reveal the larva. During this stage, growth and molting occur. Once growth is complete, the Drosophila enter the pupal stage, where it develops into an adult through metamorphosis. Upon reaching adulthood, the flies are ready to mate and produce the next generation of Drosophila melanogaster. During this experiment, monohybrid and dihybrid crosses were conducted with Drosophila melanogaster. Our objective was to examine the inheritance from one generation to the next. We collected the data from the crosses and analyzed them in relation to the expected results. MATERIALS AND METHODS For the monohybrid cross in this experiment, we used an F1 generation, which resulted from the mating of a male homozygous wild-type eyed fly with a female homozygous sepia eyed fly. Males and females are distinguished by differences in body shape and size. Males have a darker and rounder abdomen in comparison to females, which are more pointed. Another difference occurs on the forelegs of the flies-males have a small bump called sex combs. At week 0, after being anaesthitized by fly-nap, three males and three females were identified under a dissecting microscope and placed in a plastic vial with a foam stopper at the end. The vial remained on it's side until the flies regained consciousness so that they didn't get trapped by the culture medium at the bottom. We allowed the Drosophila to incubate and reproduce for a week. After one week, the vial contains many larva in addition to the F1 generation flies. Next, we removed the F1 generation flies to prevent breeding between the two generations. Acting as Dr. Kevorkian, we gave the F1 generation a lethal dose of the seemingly harmless anesthesia, fly-nap. A trumpet solo of "Taps" played in our minds as we said goodbye and placed them in the fly morgue. We allowed the F2 larval generation to incubate for two weeks. The experiment called for one week of incubation, but Easter fell during that week which interfered with our lab time. After the two weeks, the F2 flies were also terminally anaesthetized. Only, before saying goodbye, we separated the flies according to sex and eye color(wild-type,red or mutant, sepia), recording the results in Table 1. The same method was used it the dihybrid cross, except, instead of one trait, two traits were observed. The traits were eye-color(wild-type, red or mutant, sepia) and wing formation(wild-type, full or mutant, vestigial). The F1 generation for the dihybrid cross came from a cross between a male homozygous wild-type for eyes and wings, and a female homozygous for sepia eyes and vestigial wings. The results of this cross were recorded and appear in Table 2. RESULTS The monohybrid cross of Drosophila melanogaster produced 25,893 flies for all of the sections combined. Of those flies, 75.9% had wild-type(red) eyes, and 24.1% had mutant(sepia eyes). Overall, more females were produced than males. TABLE 1: F1 Generation Monohybrid Cross of Drosophila melanogaster (+se x +se) PHENOTYPE CLASS RESULTS RESULTS FROM ALL CLASSES NUMBER PERCENT RATIO NUMBER PERCENT RATIO MALES WILD-TYPE EYES 562 74.8% 3.0 8,960 75.4% 3.1 SEPIA EYES 189 25.2% 1 2,923 24.6% 1 FEMALES WILD-TYPE EYES 806 75.6% 3.1 10,685 76.3% 3.2 SEPIA EYES 260 24.4% 1 3,325 23.7% 1 BOTH SEXES WILD-TYPE EYES 1368 75.3% 3.0 19,645 75.9% 3.1 SEPIA EYES 449 24.7% 1 6,248 24.1% 1 The dihybrid cross produced a total of 26, 623 flies for all of the sections combined. 54.9% of the flies had wild-type eyes(red) and wild-type wings(full), 17.7% had wild-type eyes and vestigial wings, 21.3% had sepia eyes and full wings, and 6.1% had sepia eyes and vestigial wings. Again, the number of females produced exceeded the number of males. TABLE 2: F1 Generation Dihybrid Cross of Drosophila melanogaster(+vg+se x +vg+se) PHENOTYPE CLASS RESULTS RESULTS FROM ALL CLASSES MALES NUMBER PERCENT RATIO NUMBER PERCENT RATIO WILD-TYPE EYES WILD-TYPE WINGS 244 47.8% 6.3 6987 54.4% 8.6 WILD-TYPE EYES VESTIGIAL WINGS 132 25.9% 3.4 2315 18% 2.9 SEPIA EYES WILD-TYPE WINGS 95 18.6% 2.4 2727 21.2% 3.4 SEPIA EYES VESTIGIAL WINGS 39 7.6% 1 808 6.4% 1 FEMALES WILD-TYPE EYES WILD-TYPE WINGS 281 51.1% 7.0 7615 55.2% 9.3 WILD-TYPE EYES VESTIGIAL WINGS 100 18.2% 2.5 2397 17.4% 2.9 SEPIA EYES WILD-TYPE WINGS 129 23.5% 3.2 2953 21.4% 3.6 SEPIA EYES VESTIGIAL WINGS 40 7.3% 1 821 6.0% 1 BOTH SEXES WILD-TYPE EYES WILD-TYPE WINGS 525 49.5% 6.6 14,602 54.9% 9.0 WILD-TYPE EYES VESTIGIAL WINGS 232 21.9% 2.9 4,712 17.7% 2.9 SEPIA EYES WILD-TYPE WINGS 224 21.1% 2.8 5,680 21.3% 3.5 SEPIA EYES VESTIGIAL WINGS 79 7.5% 1 1,629 6.1% 1 DISCUSSION The results from the monohybrid cross for both my class and for all sections were very close to the expected results. "Theoretically, there should be three red-eyed flies for every one sepia-eyed fly. We call this a 3:1 phenotypic ratio" (So What's a Monohybrid Cross Anyway? 2). As indicated in table one, the data comes within one or two tenths of the 3:1 ratio. Therefore, the monohybrid cross was very accurate. However, the results from the dihybrid cross were not quite as accurate. Mendel hypothesized and proved that a dihybrid cross should produce a 9:3:3:1 ratio(Biology 245). In our experiment, the results from my class (both sexes) were not very close to the ratio. In table 2, the ratio shows 6.6:2.9:2.8:1. The data obtained from all classes were slightly more precise. All sections together (both sexes) produced a ratio of 9:2.9:3.5:1. There are many reasons that our results did not match the expected ratios. For example, when transferring flies from one vial to another, a few flies got away which could have a small effect on the numbers. Another factor affecting the results also happened upon transferring flies. A number of flies were imbedded in the cultural medium. We were forced to leave them there so that we didn't loosen the medium. The largest source of error in the "my class" column came from the amount of time we allowed the flies to reproduce. Since Easter vacation occurred during our lab period, our second generation flies were permitted to stay together for two weeks instead of one. This may have resulted in the F2 generation flies mating with their own offspring, thus throwing off the ratio. I feel more certain about the results in the "all classes" column since many more trials were performed and more flies were used. In any experiment, the more trials one conducts, the more accurate the results will be. This makes sense when comparing the results from my class versus the results from all classes combined. The numbers of flies used in each column make the difference in trials more evident: 1,060 flies were produced in my class, whereas 26, 623 flies were produced in all classes. In the monohybrid cross, the ratio for eye color for the females were consistent with the ratio for males. This information implies that the gene for eye color is not sex linked. Through research, I found that in Drosophila melanogaster, chromosome one is the sex chromosome. Eye color is not one chromosome one, but rather on chromosome three. Therefore, eye color in Drosophila is not sex linked(Genetics:Drosophila Crosses). In each column, the number of females produced outweighed the number of males. This may imply that the X chromosome is dominant over the Y chromosome. This would cause the X chromosome to mix with another X chromosome, producing a female, more often than it would mix with the Y chromosome, which would produce a male. As a follow-up to the experiment, I would perform many more trials than each person did for this experiment. Also, more flies could be placed in each vial to ensure even more offspring to be included in the data. I would also be sure to remove the flies after just one week to reduce breeding between generations. This experiment caused Mendel's findings to be more concrete and realistic in my mind. It made the information more than meaningless numbers. The experiment also made me realize how easily biological ideas can be proved. Our results agree with Mendel's discoveries. The only drawback to our learning was the massacre of over 26,000 fruit flies