Реферат: Cloning In The 20Th Century Essay Research
Cloning In The 20Th Century Essay, Research Paper
We have seen comic material in the movies and on television. The entertainment industry usually shows it in a humorous situation such as Danny Devito and Arnold Schwannager as genetically engineered twins while Michael Keaton was duplicated to make his life easier. Cloning is only achieved after intensive research and experimentation where as in the movies; it is made out to be as easy as 1, 2, 3. Even though animal and human cloning has only been announced recently to the public, it has been around for the many decades, and is very beneficial to our future generations.
In 1938, a German scientist by the name of Hans Spemann came to the conclusion that organisms can, in fact, be reproduced. His belief was that by transplanting the central element of one animal s cell into the egg of another animal, the animal could be reproduced, or cloned. Dr. Spemann believed that the central element or nucleus of a cell contained the genetic blueprint for the structure of the organism. He was awarded the Nobel Prize in 1935 for his discovery of what he called the organizer effect ( Bio of Hans ). After Spemenn s discovery, there were two other tries to replicate what he did. The first was in 1952, when American scientists tried by infusing the nucleus of a frog s embryo into a frog egg, but this attempt resulted in failure. In 1970, a British scientist repeated the same experiment. This attempt resulted in the development of some specimens, which died after reaching the tadpole stage. Over time, there have been many claims to cloning, but have all turned up as either frauds or they produced organisms that have died after a few days(Plutonium).
There have been instances of cloning with several types of animals beginning in 1984. Embryonic animal cells were what clones were produced from in the past. Scientists have developed a new process called somatic cell nuclear transfer, which is performed using nature cells. This is the science that was used to produce Dolly in 1997.
It has been said that after 277 failures, Dolly was finally produced. The team of scientists who made Dolly described that they removed cells from under the arm of an adult sheep, starved those cells from nutrients so they would enter a dormant state and then used an electrical charge to force the cell s pores to open. 277 different eggs and cells were fused together. Of those 277 fused eggs, only 29 survived and were implanted into 13 ewes. These ewes were to act as the surrogate mothers. Of those 29, only one sheep embryo survived. This embryo was born on July of 1996 and was named Dolly. This famous sheep was introduced to the public in February of 1997 and was named after the country music singer Dolly Parton.
Plants as well as animals can be cloned. The main difference in these two procedures is that for the past 2000 years, we have been forcing the plants to reproduce by methods of grafting and stem cutting. The main goal is to clone plants that will be superior to those plants that occur naturally. Scientists hope that these new, genetically altered plants will be more resistant to insects, viruses and bacteria with improved nutritional qualities and longer lives. This would not only benefit man, but a lot of plants are also used in the production of medicine (Clone 2: 832).
Animal cloning would also allow an effective study of human genetic diseases such as cystic fibrosis and Down s syndrome. It can even put an end to the shortage of human transplant organs by the use of trangenetic animals. These animals have been genetically altered to that their organs would be partially made up of human material (Reibstein and Reals 58). This method would once again bring the rights of animals into concern. A lot of controversy could arise in raising animals solely to produce drugs, experiment on or take organs from. Scientists feel that it may be possible to reprogram skin or blood cells so that they will grow into spare parts of tissues and organs rather than whole organisms but this would be many years into the making.
Many of these methods will not be practical in the near future but there are other cloning methods that can help those that are already alive. It can help in developing new treatments for disease, cure disease, and save lives. One disease that cloning would hopefully help would be Parkinson s disease, which is a disease of the nervous system. Scientists could manipulate cells to grow into healthy brain cells (Cloning 159).
Still another use is growing organs and/or tissues for humans. Cells can be manipulated to revert to their embryonic stage and then these cells will have the potential to grow into other issues, cells, etc. This is done through chemical signals called fibroblast growth factors. These signals “tell” the cells what to do. These same chemical signals are also used on embryos. The fibroblast growth factors tell the cells what to become. Hans Spemann found the organizer effect, which is how the embryonic cells are aligned. The organizer effect shows that “the anterior parts of it (the cell) tend to produce the parts of the head and the posterior parts of it parts of the tail (bottom).” (”Biography of Hans Speeman”)
By producing organs/tissues genetically identical to that a patient, there would be less risk of rejection and the patient would be spared from the need to take heavy medication that suppresses the immune system. Transplant patients would benefit the most from this because there are not anywhere near enough organ donors for those who need the organs. On top of that, the patients then have to wait and see if the organ is the right size and if the body will reject the organ. Human bodies attack what is not genetically alike to the specific body; thus, transplant organs are rejected at times even with the medication that tries to suppress this action. Another technique of transfer cloning obtains healthy adult cells and reprograms them “so that they are embryonic and have the potential to grow into any type of tissue.” (”Potential uses” 980) This method could be used to produce stem cells, which are undifferentiated or unspecialized, capable of being any tissue/organ. Stem cells could be used to replace the area of damaged nerve tissue, which does not regenerate. This process can also be used to grow organs for those who need them or even bone marrow.
Gene cloning can be used to produce vaccines and hormones, it already has led to the inexpensive production of insulin for diabetes and of growth hormones for children who do not produce enough hormones for normal growth. Monoclonal antibodies used the immune system to fight off disease could be injected into the blood system where it would seek out and attack a tracer element to the cloned antibody that would be able to locate hidden cancers in the body. They would attach cancer fighting drugs to the tracer and the treatment dose could be transported directly to the cancer cells (Clone 2:833).
Other recent discoveries in genetics have led to the hope of eventually being able to rewire several spinal cord nerves. Investigations of this theory have included gene study on worms, fruit flies, rats and humans. Hopefully be gaining more information on how growing nerves are guided will make it possible in the future to manipulate their growth and allow the repair of severed nerves in the spinal cord (Advances). Cloning research could make a large difference in the quality of life for a large number of people. It would not have to be used to clone humans themselves.
According to the Human Cloning Foundation, this process can help people with genetic problems; those who have a high risk for Down s Syndrome can avoid that risk by cloning… we may be able to make livers for liver transplants, and kidneys for kidney transplants. We should be able to create bone marrow for children and adults who are suffering from leukemia, and we may learn how to switch cells on and off through cloning and thus be able to cure cancer. Thus, before an artificially fertilized embryo is implanted a cell from the embryo, it could be cloned and analyzed for genes that cause diseases. This way an embryo with the highest chance of good health and survival could be selected for implantation.
Although a ban on the cloning of humans may be desirable to some, scientists argue that a ban would limit scientific research that could benefit humans. In an effort to provide an alternative to a total ban, the U.S. Food and Drug Administration declared it illegal to clone humans without FDA approval. This would prevent the cloning of human beings but would allow scientific research to continue. Researches that will allow scientists to further study the process and benefits of cloning. The filed of genetics has advanced by leaps and bounds. Cloning has gone from cutting plant stems to produce new plants to cloning frogs. Since then, a huge leap was made in the production of the sheep Dolly.
In our imaginations cloning might be the stuff of science fiction but in reality, I don t foresee my clone standing next to me, an army of Hitlers taking over the world, giving birth to “myself” or having a headless clone just hanging around waiting for me to harvest body parts as needed. I do see responsible and sensible guidelines implemented. Genetic scientists have approached cloning with caution and followed a moral code of conduct and I expect them to continue to do so. As they make advancements in genetics, we will see diseases cured, the sickly returned to good health, and other medical miracles become reality.
+ “Clone and cloning.” Gale Encyclopedia of Science, Vol.2: 832+.
+ Editor: Bridget Travers. 1995.
+ “Cloning.” Issues and Controversies on File. 18 Apr. 1997:153+.
+ “Human Cloning in the Future.” Issues and Controversies on File 18 Apr. 1997: 159-160.
+ Plutonium College earthops.org/cloning_history.html
+ “Potential Uses in Research UK news (http://www/telegraph.co.uk:80/et?ac=00064… atmo=9999999&pg=et/98/1/30/nclo130.html.)
+ “Biography of Hans Spemann” (http://www.nobel.se/laureates/medicine-1935-1-bio.html)
+ Human Cloning Foundation. The benefits of human cloning (http://www.humancloning.org)