Cloning Essay, Research Paper
In Case You Were Sleeping
On June 22nd 1999, the world was changed in such a radical way that it will never be the same. A group of Scottish scientists from the Roslin Institute did the impossible and created the world’s first genetic clone, a sheep named Dolly. She was an exact replica of her mother’s nucleic DNA, but the most incredible part was that Dolly’s DNA came from her mother’s udder, not a haploid sex cell.
What Makes This So Special
What happened with Dolly is even different from the natural process of twining, which creates two identical twins. Twinning is the result of sexual reproduction ; each donor, or “parent”, contributes one half of the fertilized egg’s genome. This fertilized egg then divides into two (or more) separate eggs, each with an identical genome, and each of these develop into genetically identical siblings (NCGR – GPI Program).
Dolly is again different from how bacteria reproduce naturally through asexual reproduction (Barth, 987). Many other organisms also do this but it happens naturally for them, though processes such as binary fission and budding.
Instead the scientists used nuclear transfer technology (Figure 1). An adult udder cell was taken from an ewe, and an early egg cell, called and oocyst, was taken from a different ewe. The egg cell was stripped of it’s nucleus and the nucleus from the udder cell was joined with the use of an electronic pulse. The egg believes it has been fertilized and begins to grow and divide like normal. It is then left to grow in a culture dish until it becomes a blastocyst, an early embryotic state. The young embryo is then implanted into a surrogate mother and is, if all goes well, a genetically identical ewe (to the udder cell’s DNA) is born 5 months later (Coglhan, Andy).
The ability to take the nucleus from any living adult mammal cell and create a new organism is quite substantial. Even 5 years ago it was believed to be impossible. The applications for this technique are immense, but so are the problems.
With every new advance we make there are complications, cloning is no exception. The largest problem is the success factor. It took over 277 egg and udder cell fusions to have a success with Dolly. This would be totally unacceptable to do with many species as the gestation time would be longer and too much time and money would be invested into miscarriages and stillborns.
Over the last three years other attempts have been made. A 3% success factor was achieved when attempting to clone male lab mice and is considered quite high (Cohen, Philip). Many of the animals born from these procedures, such as cows have died in early infancy for various reasons. Some have had underdeveloped immune systems and died from infections or other relatively easy to cure problems. (Cohen, Philip)
Another early problem was shortened telomeres. Telomeres are the ends of the chromosomes which are naturally worn off through mitosis, therefore reflecting the age of the organism and perhaps causing the signs of old age. However it was found that Dolly had shorter than usual telomeres, which could cause premature aging. This was originally one of the biggest setbacks for the researchers. However, there is contradicting evidence of this though in recently cloned, and still living, cattle. Their telomeres are unusually long when compared to those of the parent cell. No one has an explanation for this, but they are sure it has nothing to do with the difference in species. (Tenove, Chris)
It has recently been discovered that Dolly, the lamb and her mother/twin sister, are not genetically identical. They have the same nuclear DNA, but their mitochondrian DNA differs. This could make the difference between the clone being a super-athelete or a couch potato (Cohen, Philip).
The most mind boggling problem is the fact that some species may be uncloneable. Experiments done with specific types of lab mice have shown that some mice with specific traits are uncloneable, but if this applies more generally to specific species all together remains unknown, mostly because of the public’s problem with cloning (Cohen, Philip).
When Dolly was brought into this world there was a mixed reaction. Some people were overjoyed, and others immediately feared the technology. Some thought it could bring immortality, and religious cults thought it could create the perfect person but many others feared this (Cohen, Philip). They feared that millions of “test-tube babies” would be born, and the ethical battle was on. Three years later it still rages with no winner in sight, but many countries have already made laws to prohibit the use of human embryos in cloning. Their reaction is, of course, expected. Through history people have always feared change, and feared by making man more godlike they would ruin life for all of us (Bernstein, Maurice). The potential applications are too many and lifesaving for some researchers though.
Applications of Cloning
Even with all the barriers, ethical, scientific and otherwise physical, some researchers believe the good that can come from this technology is worth more than all the hardships, mostly from society and their own colleagues, that they have to endure. Pigs are currently being cloned to make their organs more “human-like”, at least from an immune system’s perspective. Some people are alarmed by this though, as there is a chance of introducing viruses that affect pigs into the human population (Cohen, Philip).
Sheep are a prime candidate for cloning as well because their organs, such as the lungs, are even closer to our own than a mouse’s is. This would allow for more efficient testing for diseases such as cystic fibrosis. Cows and other farm animals are already being cloned with human genes in order to synthesize specific proteins. Scientists hope in the future to be able to manipulate the genes in such a way to clone cows that would have lean meat, or even low-fat milk (Wilmut, Ian).
The ultimate application of cloning would be to clone specific body parts in order to replace those destroyed by disease or physical injury. This application is not only the ultimate goal of the researchers, it would be the holy grail of science and perhaps the savior to all mankind with such diseases as cancer and AIDS on the rise. Not only could you replace affected tissues, but you could replace them with 100% compatible tissues that could have been genetically enhanced to make them immune to the disease or disorder. Skin is already being cloned in labs for use in severe burn cases.
If it hadn’t been noticed already, this list of applications did not include creating an army of super intelligent, super strong clones to take over the world. Although science fiction fans would be very interested in that scenario the probability of that happening at any time, much less any time soon and without anyone noticing, is incomprehensibly small. The time and resources would just be far too much for our current state (Bernstein, Maurice).
The Jury is Still Out
It is still far too early to come to conclusions about how cloning will affect our society. There will be an impact left on society, that has already begun to happen, but whether it is a positive or negative impact is still unknown. It may remain this way until a useful product arises from the current experiments, such as enhanced drugs or cloned organs for transplant or until something goes dreadfully wrong, or governments never loosen laws that restrict the usage of human tissues in experiments. Whichever comes first, be it good or bad, will make the most impact on how we view the potential of this wondrous technology.
Barth, Frances. “Cloning.” The Volume Library. Nashville, Tennessee: The Southwestern Company: 1989. pg. 984-1002
Bernstein, Maurice M.D. Bioethics Discussion Pages. [web page] 7 May 2000; U of Southern California. . [accessed 8 June 2000]
Coghlan, Andy. One small step for a sheep. [web page] 1 March 1997; . [accessed 9 June 2000]
Cohen, Philip. Dolly’s Mixture. [web page] 4 September 1999; [accessed 9 June 2000]
Cohen, Philip. Double trouble. [web page] 6 February 2000;
[accessed 10 June 2000]
Cohen, Philip. Le clone est mort. [web page] 18 April 1998; [accessed 10 June 2000]
Cohen, Philip. Cults bizarre vision rekindles cloning debate. [web page] 31 May 1997; [accessed 9 June 2000]
Cohen, Philip. Designer Donors. [web page] 25 March 2000;
[accessed 9 June 2000]
Levine, Louise. “Cloning.” Groiler Multimedia Encyclopedia. 1999 ed. CD-ROM. Danbury, Connecticut: Groiler Interactive, 1998
NCGR – GPI Program. Genetic Cloning vs Genetic Twinning. [web page] 7 August 1997; . [accessed 9 June 2000]
Stewart, Colin. “Cloning.” TIME Magizine. . 1997.
Tenove, Chris. Forever Young. [web page] 6 May 2000; . [accessed 10 June 2000]
Wilmut, Ian. Potential benefits of cloning and Nuclear Transfer. [web page] 3 March 1998; Roslin Institute. [accessed 11 June 2000]Figure 1 – The creation of Dolly the sheep. Note that egg and udder cell were removed months before the experiment. Picture courtesy of New Scientist
Комментариев на модерации: 2.