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...
Cloning has become a very contentious subject. The issue of cloning has moved from the scientific arena into the cultural, religious and ethical centers of debate, for good reasons. The scientific implications of cloning affects a wide range of social and ethical concerns. The theory of cloning questions many essential areas of ethical and philosophical concern about what human life is and raises the question whether we have the right
Cloning The debate about human cloning was carried out within the field of science fiction and fantasy, until recently. With the victorious cloning of the sheep Dolly in 1997, it became obvious that earlier or later, scientists might be able to clone human beings too. There is both encouragement and disagreement for this likelihood. Though cloning has been explained by newspapers and magazines as an exhilarating step onward that allows genetic
Cloning is no longer the stuff of science fiction, but is a reality that has become a serious subject of hot debate around the globe. At issue are the ethical, scientific, moral and economic implications of cloning. In October 2004, David Stevens, Executive Director of the Christian Medical Association confronted scientific duplicity and specifically challenged the International Society for Stem Cell Research asking to stop misleading the public and the media
Legal costs might also haunt governments that allow cloning research. To prevent complications related to direct government investments in cloning research, legislation could open the door for privately-funded cloning research projects while at the same time banning federally- or state-funded research projects. However, most opponents of cloning cite the ethical costs involved in cloning legislation. Opponents of stem cell research sometimes "argue that permitting nuclear transplantation would open the door
For example, the most common instrument used in cloning today is known as a "micromanipulator," described by Baird as being an expensive machine that requires the use of a skilled technician to capture an egg cell under the microscope, insert a very fine needle to suck out its nucleus, and then use another needle to transfer a nucleus from the animal to be cloned. "This process is tricky and
Cloning? Cloning is the exact replication of a single individual gene or a part of a single individual gene achieved with the use of specialized DNA technology. The result may be used for further scientific research or for nay other purposes that it was cloned for. The Human Genome Project that conducts cloning experiment on a regular basis refers to the entire process as the method of 'cloning DNA',
Our semester plans gives you unlimited, unrestricted access to our entire library of resources —writing tools, guides, example essays, tutorials, class notes, and more.
Get Started Now