Cloning Our Group Is a Term Paper
- Length: 11 pages
- Subject: Genetics
- Type: Term Paper
- Paper: #52820690
Excerpt from Term Paper :
Experiments in the late nineteenth century on frogs provided the groundwork for cloning (McKinnell 9-10).
The method used a decade ago for the successful nuclear transplantation in amphibians required that the egg be enucleated, which meant removing the maternal hereditary material contained in the egg nucleus. Other hereditary material contained in the nucleus from a body cell would then be placed in the enucleated egg, and the resulting clone would be parentless:
Biologically, a mother is a mother by virtue of the fact that she contributes hereditary material via the chromosomes of an egg. . . A father is a biological father by virtue of the fact that he has contributed hereditary material via his sperm. Since no sperm has participated in the development of the cloned individual, there is no male parent (McKinnell 10-11).
Cloning higher animals has proven to be difficult, but scientists have persevered and have produced clones of livestock, including sheep. Researchers in Scotland recently succeeded in cloning cheep using a technique that has the potential to produce hundreds of animals. The researchers expect to combine the method with genetic engineering to create animals with specific traits. The method is called nuclear transfer and replaces the nucleus of an immature egg with a nucleus from another cell. In earlier methods, scientists obtained replacement nuclei directly from cells in embryos, but the new method uses nuclei from cells grown in a laboratory culture. An embryo has no more than 30 or 40 usable cells, while a culture usually features an almost endless supply. Genetic engineering with these donor cells is more feasible because a lab culture can supply so many cells to manipulate. A company would first select cells for cloning from prize animals and would then improve them further, such as with a gene that makes the animals produce milk rich in a therapeutic protein. This experiment was conducted with the embryo cells of Welsh mountain sheep grown in the laboratory. The researchers then transferred 244 of the nuclei to the stripped-down eggs of Scottish blackface ewes. This experiment produced five genetically identical Welsh mountain lambs, two of which died within 10 days of birth for reasons that remain unclear (Adler 148).
This experiment at the Roslin Institute in Scotland comes after a decade of the use of genetic technology to produce biologically identical copies of animals, but the old method limited the number of clones that could be produced. The new method makes it possible, when perfected, to produce thousands of identical sheep and cattle at a time. It is suggested that this will make it possible one day to produce cattle with leaner meat and cows that produce low-fat milk. The new method allows greater fine-tuning and more precise genetic changes in the cells used (Nichols 55).
Such experiments are only a portion of the types of work being done in this area. Recombinant DNA is DNA molecules derived from different sources that have been artificially spliced together in vitro to form novel hybrid DNA molecules not normally encountered in nature. Modern genetic engineering techniques based on recombinant DNA permit genetic exchanges between species that do not normally interbreed thus offering the opportunity for us to transcend the limits imposed by nature on hereditary processes. Using these techniques, scientists can manipulate genes individually by directly modifying the DNA molecules in which genetic information is encoded. This means that the technique has the potential to transform the genes of all species into a global resource that can be used to shape novel life forms obedient to the scientist rather than to the dictates of natural selection (Suzuki and Knudtson 115-116).
The sorts of genetic changes science has been seeking can be seen in the recently announcement by a combination of U.S. And British researchers that they have genetically engineered sheep and goats to secrete drugs in their milk as a means of giving the biotech industry a streamlined means for producing many pharmaceuticals. The livestock produced in this manner are called transgenics because their cells contain foreign genes which direct the production of proteins with medicinal purposes. Goats developed at Tufts University and Genzyme Corporation in Cambridge, Massachusetts, for example, bear the gene for TPA, or tissue plasminogen activator, a drug used to dissolve blood clots in heart-attack patients. To create the livestock, genes were inserted with a needle into fertilized eggs which were then returned to the female's uterus. Only a small fraction of offspring grew up bearing the foreign genes. Today, dozens of drugs are made in vats filled with genetically engineered bacteria, which are much easier to manipulate genetically than mammals, but milk can contain 100 to 1,000 times the drug concentration of a lab culture. Before livestock start producing drugs commercially, though, someone must invent ways to extract the drugs from milk, which is a trifling problem compared with the decade it took to develop transgenic animals ("Animal Pharmacy" 10)
Stem Cell Research
Cloning is also involved in stem cell research, which has itself been controversial because it has become enmeshed in the abortion debate. The issue of stem cell research has been argued for several years now and remains a contentious question, whether or not to allow this type of research. Those who argue for it point to the possibility that such research will lead to treatments or cures for a variety of ailments including diseases like diabetes and trauma damage like spinal cord injury. To date, none of these potential cures has been realized. Those who oppose such research claim either that this line of research is not as promising as proponents claim or that research on human stem cells is a moral issue and should be prevented for that reason.
This sort of research has been a possibility since November 1998, after two decades of research, scientists successfully isolated and cultured human stem cells, or "undifferentiated" cells, which may be considered the building-block cells of the human organism. These develop into the 210 different kinds of tissue in the human body. Medical researchers believe these cells may allow them to incubate tissue that can be used to treat people suffering from Parkinson's, Alzheimer's, heart disease, diabetes, and other cell-degenerative afflictions. Scientists harvest stem cells from embryos acquired at fertility clinics and tissue recovered from fetal cadavers from abortion clinics, but some ethicists are concerned that researchers may also use in vitro fertilization (IVF) techniques to create their "in-house" embryos (Cowley 52).
Stem cell research is related to cloning and is also called therapeutic cloning, a term that refers to the cloning of cells the removal of stem cells from the pre-embryo in order to produce tissue or a whole organ to be transplanted back into the person who supplied the DNA. The reason for this is "to produce a healthy copy of a sick person's tissues or organ for transplant," which "would be vastly superior to relying on organ transplants from other people" ("Embryo Cloning, Adult DNA Cloning and Therapeutic Cloning" para. 4). For one thing, the problem of rejection is overcome in this manner without the need for specialized drugs. The supply of tissue that could be cloned is virtually unlimited, and this would eliminate waiting lists for transplants.
Given the fact that such research is highly speculative and can be conducted on adult stem cells for most purposes, embryonic stem cell research should not be allowed because of the threat it poses to the unborn, with the possibility of future harvesting of fetuses for this purpose. The Constitution protects human life, and stem cell research could threaten it.
One of the benefits of human cloning has already been noted -if it could produce organs for transplant, it would do so for more people and in a way that avoids the need for the lifelong use of immunosuppressant drugs ("Embryo Cloning, Adult DNA Cloning and Therapeutic Cloning" para. 4). This would be only one of the possibilities for curing disease by means of cloning technology, and among the other possibilities raised are curing diabetes, Parkinson's, and other afflictions; reversing the bad effects suffered from heart attacks; avoiding the risk of down's syndrome; curing Tay-Sachs disease; reversing liver failure and kidney failure; cloning bone marrow for treating leukemia; and curing cancer. The technique may also make it possible to reverse the effects of spinal cord injury. Cloning technology could be used to test for and perhaps cure genetic diseases (Smith paras. 1-16).
Cloning techniques can help infertile couples have children, for the method would be more successful than current efforts in this area. Current infertility treatments are thought to be less then ten percent successful, while human cloning would increase this percentage considerably (Smith para. 4). Cloning technology has the potential to produce more and healthier children…