Реферат: Cloning Essay Research Paper The idea that
Название: Cloning Essay Research Paper The idea that Раздел: Топики по английскому языку Тип: реферат |
Cloning Essay, Research Paper The idea that humans might someday be cloned has started sounding less like a science fiction novel and more like a genuine scientific possibility. On February 23, 1997, The Observer broke the news that Ian Wilmut, a Scottish scientist, and his colleages at the Roslin Institute were about to anounce the successful cloning of a sheep by a new technique which had never been successfully used before in mammals. This technique involved transplanting the genetic material of an adult sheep, obtained froma differentiated somatic cell, into an egg from which the nucleus had been removed. The resulting birth of a sheep named Dolly on July 5, 1997, was different from prior attempts to create identical offspring since Dolly contained the genetic material of only one parent, which therefor emade her a “delayed” carbon copy of a parent which had contributed her genetic makeup, with a member of the opposite sex only filling in her genetic makeup wherever it was absolutely necessary in the creation process. Since the birth of Dolly public debates have sprung up all over the world. Although cloning of humans may be clinically feasible, discussion of the ethical, legal, and social issues raised are important. Cloning is just one of the several techniques potentially available to select, control, or alter the genome of an offspring. The developement of such technology poses an important challenge: how to ensure that the technology is used to enhance, rather than limit, individual freedom and welfare. A key ethical question is whether a responsible couple, interested in rearing healthy offspring biologically related to them, migt ethically choose to use cloning, or other genetic selection technique for that purpose. The answer should take into account the benefits sought through the use of the techniques and any potential harm to offspring or to other interests. The most likely uses of cloning would be far removed from the bizarre or horrific scenarios that initially dominated media coverage. Clonging humans is actually quite simple, when thought of relevently. The procedures used in cloning human embryos are very similar to that of cloning animal embryos. To clone a human embryo, one must first acquire a sperm cell and a mature egg cell and combine them. The “home made” embryo is placed in a petri dish and allowed to develop into a mass of two to eight cells. Next a chemical solution is added that dissolves the zona pellucida that covers the embryo. The zona pellucida is a protective preotein and polysaccharide membrane that covers the internal catchword of the embry, and provides the necessary nutrients for the first several cell divisions taht occur within the embryo. After the zona pellucida is dissolved the cells within the embryo are freed. These two to eight cells are then collected by the researchers and placed in seperate petri dishes. These embryonic cells are called blastomers, or cells that are part of a hollow ball of cells known as the blastula. The embryonic cells are then coated with an artificially produced zona pellicuda. The individual cells then are considered new embryos, all of which share the exact genetic information and composition. These cells will continue to divide and eventually will form a human being if allowed to develop. The main issue as to whether or not human cloning is possible throught the splitting of embryos began in 1993 when experimentaion was done at George Washington University Medical Center in Washington, D.C. There Dr. Jerry Hall experimented with the possibility of human cloning and began this moral and ethical debate. There it was conducted that cloning is not something that can be done as of now, but it is quite a possibility for the future. These scientists experimented eagerly in aims of learning how to clone a human. Shannon Brownlee of U.S. New and World Report writes, “Hall and other scientists split single human embryos into identical copies, a technology that opens a Pandora’a box of ethical questions and has sparked a storm of controversary around the world.” They attempted to creat seventeen human embryos in a laboratory dish and when it had grown enough, seperatedthem into forty-eight individual cells. Two of the seperate cells that survived for a few days in the lab developed into new human embryos smaller than the head of a pin and consisted of thirty-two cells each. Although we have yet to truly clone an actual human being , when this experiment occured, it caused almost an ethical emergency. Many questions were asked, but they were all related to one thing. The question is, can we and should we use the biotechnologies of genetic manipulation and cloning to improve the human condition? What are exactly the percieved risks and benefits of eugenics? Some people may think that biologist are cloning human embryos only to see how far they can push the scientifica envelope, but there are many legitimate reasons for investigating cloning. Embryologists believe that research into cloning could help improve the life of future generations. Many biologists believe that they have a personal duty to the improvement of society, perhaps even a moral obligation. To this end the techniques of embryonic cloning and alteration have been offered to society as an option for the improvement of humanity. Doctors hope that by being able to study the multiple embryos developed through cloning, they can determine the causes of spontaneous miscarriages. Contraceptive specialists believe that they can determine how an embryo knows where to implant itself, they can develop a contraceptive that would prevent embryos for implanting themselves in the uterus. There are many excited parents looking forward to this breakthrough in technology. By looking at the many different reasons for cloning a child, one can better understand why it may seem appealing to parents. Cloning form an already existing human will provide the opportunity for parents to pick their “ideal” child. They will be able to pick out every aspect of their child and make sure that it is perfect even before they decide to have it. For example, they can choose their hair and eye color, and build almost exactly by looking at the individual they were cloned from. If the husband were the source od DNA and the wife provided the egg that recieved the nuclear transfusion and then gestated the fetus, they would have a child biologically related to them and would not need to rely on an anonymous gamete or embryo donation. Of course, many infertile couples might still prefer gamete or embryo donation, or maybe even adoption. But is there really something inherently wrong with wishing to biologically related to one’s child, even when this goal cannot be reached through sexual reproduction? A second plausible application would be for a couple at high risk of having offspring with a genetic disease. Couples in this situation must now choose whether to risk the birth of an affected child, to undergo prenatal and preinplantation diagnosis and abortion or the discarding of embryos, to accept gamete donation, to seek adoption, or to remain childless. If cloning were available, however, some couples , in line with prevailing concepts of kinship, family, and parenting might strongly prefer to clone one of themselves or another family member. Alternatively, if they already had a healthy child, they might to use cloning to create a later born twin of that child. In the more distant future, it is even possible that that the child whose DNA was replicated would not have been born healthy, but would have been made healthy by gene therapy after birth. A third application relates to obtaining tissue or oragns for transplantation. A child who need an organ or tissue transplant might lack a medically suitable donor. Couples in this situation have sometimes concieved a child in hope that he or she would have the correct tissue to serve, for example, as a bone marrow donor for an older sibling. If the child’s disease was not genetic, a couple might prefer to clone the affected child to be sure that the tissue would match. It might eventually be possible to procure suitable tissues or organs by cloning the source DNA only to the point in which stem cells or other material might be obtained for transplanation, thus avoiding the need to bring a child into the world for the sake of obtaining tissue. Cloning a person’s cells up to the embryo stage might provide a source of stem cells or tissue for the person cloned. Clonign might also be able to enable a couple to clone a dead or dying child so as to have that child live on in some closely related form, to obtain sufficient numbers of embryos for transfer and pregnancy, or to eliminate mitochondrial disease. cer research is possibly the most important reason for embryo cloning. Oncologists believe that embryonic study will advance understanding of the rapid cell growth of cancer. Cancer cells develop at approximately the same phenomenal speed as embryonic cells do. By studying the embryonic cell growth, scientists may be able to determine how to stop it and also stop cancer growth in turn. Another important area of embryo cloning research is embryonic stem cell developement. Stem cells are undifferentiated cells that can develop into almost any type of cell in the body. These cells are not attacked by a person’s immune system, because of their fast developement and undifferentiated status. Many doctors believe that these stem cells could be used in treatments for brain and nerve system damage. In adult humans, when damage to nerve tissue takes place, the nerve tissue does not regenerate and replace the lost tissue. However, since the stem cells are undifferentiated they could theoretically be used to replace the damaged cells. Human embryo cloning is needed for the implantation of stem cells, because of the large amount of cells that would be needed. Genetic screening is a branch of cloning that is already being used in hospitals in England. Parents who have histories of genetically inhereited diseases, such as cystic fibrosis, can use embryo screeninhg to deteremine if their child has recvieved the defective gene. Several embryos can be developed via invetro fertilization procedures, and then be cloned. The DNA from one of the cloned embryos would then be removed and standard genetic testing, using riflips, would be used to detect whether or not that embryo contains the genetic disease. If the cloned embryo does not contain the defective gene, then one of the other identical embryos can be used for implantation in the parent. This would almost guarantee that the child would be free of genetic disease. Perhaps a more questionable use of cloned embryos is for spare parts. It is possible that parents could decide to use one cloned embryo for implantation and eventual birth of a child, and save any spares by freezing them. If the child were to become critically sick, and need a bone marrow transplant, one of the frozen embryos could be thawed and implanted into the uterine wall for developement of another identical child. The bone marrow form this child could then be used to help save the life of this child, perhaps even without the necessity of carrying the child to full term. This again raises the question of what moral status a fetus should have, if any at all? Using cloning to produce offspring for the sake of their organs is an issue that must be faced and question whether or not it is morally right. No one will say that it is okay to kill a human being for the sake of their organs, but many have no objection to cloning thousands of individuals that look alike. Technology seems to take away many of the moral that we have worked so hard to install in society. Most people seem to only want to cater to their own needs and do not bother to consider the consequences that society and the clone may have to face. The issue of invetro fertilization among embryos only leads the public to fear what may happen once cloning takes over, if it does. Probably one of the most asked questions about the possibility of a world of clones is how will it feel to be one clone among that of hundreds? Imagine walking down the street and seeing hundreds of people that are identical to you, but just go by different names and dress differently. Cloning can be used to help an individual live, but what will be the cloned individuals view on life? |