Genetics

Over the past several years Genetics has become a leading link to understanding how our body works. By mapping out deoxyribonucleic acid, or DNA, scientists plan to find cures for various diseases, develop better, more efficient drugs, grow new organs, evaluate environment hazards, and eventually build a human being. Inside of every single cell in our bodies there are 46 chromosomes that are made up of DNA. Half of your chromosomes are inherited from each parent, DNA is strung along the chromosomes. DNA is the living instructional manual found in all living organisms. The building block letters of DNA are Adenine, (A), Thymine, (T), Cytosine, (C), and Guanine, (G). These are repeated over and over again about 3 billion times in our body alone. DNA can be subdivided into genes, with each gene carrying the information on how to produce a unique protein. Each gene consists of three of the building blocks placed together. Along the stretches of DNA, genes tend to occur in clusters, like cities separated by vast emptiness. When the DNA is collected all together you have a genome. In the past scientists believed that there was more than 100,000 genes in the human genome, but recent studies by Celera Genomics and many other scientist based teams, have found that the number of genes to be 35,000. (Article #1)

This new found information has made some biologists ecstatic and has wounded the pride of others. “There are many people who are bothered by the fact that they don’t seem to have (many) more than twice as many genes as a fruit fly,” said Eric Lander, director of the Whitehead Institute Center for Genome Research. “It seems to be some kind of affront to human dignity.” The 30,000 genes in our body compared to the 13,600 in the fruit fly does seem to raise questions about why we have the abilities to do so much more when we don’t have that many more genes in our genome. Even though all creatures share the same DNA code, some people still believe that there is a step-change between the rest of nature and humans that separates us from them. The Human Genome Project, starting in the 1980’s, is a research program designed to construct a detailed genetic and physical map of the human genome, determine the complete sequence of human DNA, localize 30,000 to 35,000 genes, and perform similar analysis on the genomes of several other organisms. Every species has its own genome.

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Every individual animal within a species has its very own specific genome. Unless you are an identical twin your genome is different from everyone on earth – and from everyone who has ever lived. Even though you have your own distinct genome, it is still recognizable as a human genome. Analyzing the human genome will give us insights into why people like the foods they do, why certain people die of heart disease and others of cancer, and why some people are outgoing and others are paralyzed by shyness. We will also be able to know what body shape your children will have, the number of calories they are able to burn off in rest, and the types of sports they will excel at and enjoy. Studying the genome can related to a number of things, you can study the whole genome, or only a small part. You can study the sequence, or function of a specific gene. We are able to observe what happens when something goes wrong with a gene, and how it affects our life and body.

Certain diseases are cause by mutations in a particular gene such as Blindness, cancers, bowl disorders, Leprosy, arthritis, Turner’s syndrome, Down Syndrome, and many other types of diseases. These genetic diseases are caused by changes (mutations) in the DNA sequence of a gene or a set of genes. This can happen at any given time, from when we are a single cell to when we are close to 100 or older. Some scientists believe that there are specific disorders genes that cause the disease, but it is a mutation that causes the normal genes to operate improperly. So to clarify all the mishap it is better to say that there are mutated genes that cause genetic disorders. In some diseases such as Down Syndrome and Turner’s Syndrome, entire chromosomes, or large segments of them, are missing, duplicated, or otherwise altered. Single-Gene disorders result when a mutation causes the product of a single gene to be altered or missing. Sickle-cell Anemia is an example of this type of disorder. Mutations in the beta-globin gene cause the blood cells to become distorted and take on a sickle shape.

This makes traveling through the blood vessels hard and they begin to clog in the narrow passages, causing various problems within the body depending on where the clog is at. Multifactorial disorders result from mutations in multiple genes, often coupled with environmental causes. The complicated bases of these diseases make them strenuous to study and treat. Some examples of this type of disorder are heart disorders, diabetes, and cancers. Certain kinds of thyroid cancers are accumulated by malfunctioning genes, such as Familial papillary thyroid cancer, and Medullary thyroid cancer (Article #5). Cancer is caused by certain changes in our DNA sequence. But cancer is not developed by one mutated gene, its the accumulation of many defected genes. This can happen through inheritance of mutations or addition of new mutations during the life span of an organism. Additions of new mutations can come from exposure to the sun, UV rays, infection by certain viruses, spontaneous mutations and changes in copying the DNA during the aging process.

The genetic basis of cancer is possible by the cancerous cell dividing at inappropriate times. This could mean that the cells either do not receive the signal to stop dividing or they do not require outside signals to start dividing, so they divide when they feel like it. When cancerous cells come in contact with other neighboring cells they do not stop dividing like normal cells do, but they pile up and form a tumor. Cancerous cells also have the ability to invade healthy tissue, leading to the spread of cancer throughout the body. Scientists were able to pin down the exact gene that is responsible for prompting people’s internal wake-up alarms. A mutation in this gene can cause the person to wake up at very inappropriate times and causes them to become tried in the middle of the afternoon. The mutation was found in the human Per2 gene on Chromosome 2. This is common to many people the statistics show 1 in every 10,000 all the way up to 1 in every 100,000 people. There are a large quantity of people that don’t realize that it is a disorder so they never come in for treatment (Article #3) Colourblindness is another of the many generic disorders. It is found in the X chromosomes which is passed down from the female, never the male.

If a woman with the gene that entitles Colourblindness has a girl, the X chromosome of the baby will cancel out the colourblind chromosome (X) a majority of the time. There is a slim chance that when the X chromosome of the baby is weak the colourblind X will prevail and the girl will be born colourblind. Females are the only carriers of this generic trait, very rarely does a female get the trait. If that same woman were to have a boy, the X chromosome will predominate the Y chromosome and the boy will indefinitely be colourblind. The ratios of this disease are very different for men and women, 1 in 12 for men, and 1 in 250 for women. Inherited genetic mutations arise about twice as often in men as in women (Article #6) Scientists have found that a retinal gene appears to be responsible for at least some of the cases of macular degeneration, or blindness. The gene, which plays a role in the metabolization of a fatty acid called DHA, has become defective and does not perform its assignment accordingly. This suggests that people with the defected genes may have trouble using the fatty acid in normal cell mechanisms.

This leads to the deterioration of the macula, a central part of the retina responsible for sharp, central vision. The loss of this vision limits what a person can do, such as driving which is no longer acceptable, they have trouble reading, and they lose all peripheral vision. This defective gene is past down from generation to generation. To help cut back on the problems that can be caused by eating foods that are high in DHA, such as salmon, shellfish, eggs, tuna, liver, and many more (Article #2) The entire genetic sequence of the disease labeled Leprosy has been deciphered. This shows that with genetic sequencing of different organisms, such as the Leprosy Bacterium, is extremely helpful in finding new, efficient treatments and drugs. In the case of Leprosy it also help scientists to calculate how to grow the bacterium in a laboratory which was impossible up to now (Article #8). Ankylosing Spondylitus, or spinal arthritis is also formed from gene mutation.

The gene attacks the spine making it rigid as a poker, the extreme case, to just not allowing to move easily, the moderate case. With learning how the gene is able to make this happen we will be able to treat this, and maybe even cure it (Article #7). Other disorders are not caused by malfunctioning genes or abnormal chromosomes, but certain viruses can infect a gene and that gene will multiply with that infections written in it. AIDS is a worthy example of this type of disorder or disease. AIDS is cause by an infection with the HIV virus. The HIV virus infects an organism incorporating its own DNA into the chromosomes of the infected cell. When this cell divides, the viral DNA is inherited by all the daughter cells of the infected cell. So in a way the infected cell now has a genetic disorder, caused by the introduction of a new DNA into its chromosomes. The viral DNA will not transfer onto the next generation because the sperm and egg cells of the organism are not daughters of the infected cell. Scientists have recently been able to manipulate a skin cell to turn into heart tissue.

This can be radically helpful in the production of islet cells that produce insulin needed for diabetes. The scientists “turned the clock back” on the skin cells to produce stem cells, which have the ability to develop into any desired type of cell, from nerve to liver to muscle. Then they manipulate the stem cell to become a heart tissue. This could be a breakthrough for diabetic people, eliminating the daily insulin shots, and making live just a little it easier (Article #18). Tests with possible cures are been research continually, such as with tobacco plants that contain a human gene. The gene interleukin10 can be massed produced to help treat bowl disorders.

Using genes from other living organisms are growing more common in science (Article #4). To stop the wide shortage of organ transplants needed, scientists have started researching “humanized” pig organs. The birth of a litter of genetically modified pigs have started this research. Each of the pigs has a “marker gene” introduced into its genetic code. This produces a knock-out pig, where scientists will knock out the gene that leads to the human immune system. This will eliminate the rejection of the pig’s organs when placed in the human body. The process is called Xenotransplants, and it could start in as little as 4 years (Article #19) In the same sense scientists have been able to turn a plant’s leaves into petals, allowing nurseries to produce plants that bear flowers where leaves were. This is possible by five genes that are manipulated, either by traditional breeding, or by genetic engineering. Breeders will be able to make colourful double flowers in which stamens and leaves grow into petals and enhance the fragrance. This not only could help the nurseries but the drug industry as well, by allowing them to grow greater quantities of therapeutic chemicals that come from flowers (Article #17).

Additional traits can be discovered by sequencing the genes. Not only will scientists be able to see whether or not you have a fatal disease, but they will be able to envision what type of body type your child will have, what kind food they will have a taste for and whether they will be outgoing or paralyzed with fear about leaving the house. There are innumerable amount of traits that we will be able to see when we look at a persons genes. What kind of sports they will like, whether they will be overweight or underweight, how many calories they burn at rest, and whether they are a psychopathic killer (Article #9). We will be able to know ahead of time what kind of lives our children will lead, in some ways this is a good thing because it will prepare us for what type of parenting we have to do. But in other ways if we find out what likes and dislike our child will have we will have the choice, if we want this child or not, this exact thought raises many questions about the morality of genetic sequencing. Scientists have just encountered the gene that controls the height of humans also governs life and death, meaning that short people are genetically programmed to live longer than tall people.

Using Nematobe C.Elegan, worm-like creatures, scientists eliminated these genes and the result is either mutant giant, or dwarf worms. They discovered that the genes that were “knock out” which produce growth hormones, also influence life expectancy. The lower levels of growth hormones, the longer the life expectancy. Even though it was only tested on C. Elegans, human have the same insulin-based growth system, so it applied to humans as well (Articles #20,25). A discovery has been made that there is a gene that explains why moderate drinking can prevent heart attacks. This gene, or variants of it, makes the body break down alcohol very slowly which raises the levels of heart-protecting “good cholesterol” in the blood. Drinkers with this gene were found to have a sharply lower risks of heart attacks than those that dispense alcohol at a faster rate. The gene produces enzymes called alcohol dehydrogenase that breaks down alcohol. The gene either breaks down the alcohol quickly or slowly. You inherit one of the genes from each parent, so you can have two fast genes, two slow genes, or one of each.

Those who have two slow genes and average one drink a day have a 85% less risk of a heart attack than those who have two fast genes and hardly drink. With conditions such as obesity, overdose of alcohol, smoking, and a history of heart illness the risk was still 35% lower (Article #16). Jurrassic Park the movie directed by Steve Speilberg, based on a book by Michael Crichton, has raised many questions about the correctness of taking DNA found in fossils and decoding it. Geologists right now are extracting the DNA from prehistoric bugs’ stomach. If the chance that the DNA turns out to be belonging to a dinosaur they want to decoded it and possibly clone a dinosaur.

Cloning is made from a single adult cell joined with an egg cell, the genes of which have been removed, so all the geologists need from the DNA of a dinosaur is the adult cell, and an egg cell. If the geologists decide not to clone the dinosaurs then they will use the DNA to find out a little more about dinosaurs and the environment in which they lived (Article #10). Apart from just studying the DNA and sequencing the genes, the knowledge of the DNA can be used in fighting crimes. Any type of body fluid and cells can be used to find out who was present at the scene of a crime. Evidence such as sperm, blood, pubic hair, skin cells, and saliva can be taken into a lab and studied to find out who exactly it belongs to. This is accomplished by searching a computer from a DNA Databank. A DNA Databank keeps records on the DNA of everyone they possibly can, for use in such situations as a crime scene investigation. Once the investigators have a list of possible people that are suspected, they now go and get a swabbing of the inside of their mouths for further testing.

People have rejected this, calling it an invasion of privacy. They believe that if employers were to be able to have access to the DNA Databank they would know all about their employee including diseases or disorders, characteristics and traits. Meaning that if your employers looks at your DNA and finds that you have a history of heart disease in your genes and they believe that you are not fit for the job they can fire you on that account. This is a downfall of keeping DNA files on hand, they can be used against people, not just to help them (Articles #11,12,13,14,15) Scientists have not just been mapping the code of human and animals, but of plants as well. They have been able to genetically modify plants to help them survive longer and produce better food, flowers, or fragrance depending on what they want enhanced. Genetically Modified foods have become more common in recent years. It was mostly grains that have been engineered with genes from non-grain species that make the plants resist insects or tolerate pesticides. So a farmer can spray his crops with a pesticide and have it kill everything in its field except his harvest.

There are some problems with this, such as allergies in humans. Scientists have yet to figure out whether or not people can develop allergies towards GMOs, but some people don’t want to take the chance. The pesticide resistant plants could jump to wild plants, creating “super-weeds” or could harm valuable insects by making their food unfit to eat, such as the Monarch butterfly. The Genetically Modified Atlantic and Pacific salmon are growing faster than normal salmon, if the super-salmon were to escape from the production plantations, they could mate with normal salmon and corrupt their whole genetic pool. There is also problems with patent genetically modified plants, if a person suspects that his neighbor was stealing his super-seeds, the only way to prove he’s not is to spray his field. If the crop dies then he is not stealing the crops, but he lost all that years harvest. If the crop lives, then the company can sue the neighbor.

So you can see that there is a number of problems that could arise with releasing the GMOs. Some Health officials don’t agree with Genetically Modified foods, claiming that it is unhealthy and dangerous to humans and the environment, if not properly controlled. Right now in Canada they are looking for better ways to control GMOs and the sale of them. Officials believe that their will be a lot of problems with GMOs and how people will react to them being on the shelf, they think that there will be destruction of fields and food products just like the reaction in Europe last year. (Articles #21,22,24) After figuring out the genome of humans there is still Protenome, a complete listing of the 250,000 or so proteins that the 35,000 genes are capable of making.

Proteins can vary in health and disease, and the long chains of amino acids do not string out but curl up on themselves in complex 3D shapes, making it indefinitely harder to break the code. “Most of biology happens at the protein level, not the DNA level,” Dr. Craig Venter of Celera Genomics points out. Scientists not only have to figure out what the listing of proteins is but how they change in disease and how they fold. This is dubbed the “Greatest unsolved problem in biology.” (Article #27) As you can see there is still a long way to go in finding out everything there is to know about Genetics. But when we do find out everything about Genetics and the human body, there is nothing left to the imagination, and a part of that will be sorely missed.

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