Cloning Essay Research Paper On February 24

Cloning Essay, Research Paper

On February 24, 1997, the scientists at the Roslin Institute in Edinburg, Scotland announced their success in cloning an adult mammal for the first time. The cloned sheep was named Dolly. She was the first animal cloned from a cell taken from an adult. It was an accomplishment than science had declared impossible. In June, 1997, the National Bioethics Advisory Commission issued its recommendation that a ban be placed on all efforts to create a child through cloning or somatic cell nuclear transfer. They urged that the current moratorium on federal funding of human cloning research be continued, and requested private agencies also restrain from such work. At the same time they recommended that this issue be reevaluated after a 3-5 year period of study and reflection.

Dolly was a clone of the sheep (her genetic mother) who provided the udder cell. The package of genes in the nucleus of that udder cell contained exactly the same repertoire of genes as all the rest of her mother’s cells and so Dolly’s genetic makeup was identical to her mother’s. What was novel about Dolly was that she was the first unequivocal mammalian clone. Lower vertebrates had been cloned in the early 1960s when it was shown that a nucleus taken from an adult frog cell transplanted to a frog egg whose own nucleus had been destroyed was able to direct the development of that egg into a swimming tadpole. It was this experiment that first indicated that the genetic content of all our cells, despite the differences between a skin cell and kidney cell, must be more or less the same and retain all the genetic information necessary for an egg to develop into a whole organism.

The cloning of Dolly brought up the possibility of cloning humans. It is illegal in England and Norway. With opinion polls showing overwhelming opposition to cloning human, President Clinton ordered a ban on all federal support for human cloning research and charged the National Bioethics Advisory Commission to report on the ethics of human cloning. This eighteen-member panel of scientists and non scientists concluded that attempting to clone a human being was at this time…morally unacceptable. They recommended continuing the president s ban on the use of federal funds to support cloning of humans, and called federal legislation to prohibit anyone from attempting to create a child through cloning.

California banned human cloning. Meanwhile, the real action was quietly going on in the laboratories, outside the periphery of the public eye. Federally supported experiments in cloning monkeys for use in AIDS vaccine and other research was continuing outside the limelight. What can be done with monkeys can probably be done with people. We are laying the groundwork, one of the scientists said. (Gin Kolata, New York Times)

Dr. Steen Willadsen, one of the scientists who developed techniques used to make Dolly, said it was just a matter of time before the first human is cloned. He is anticipating that cloning will inevitably become an accepted medical procedure, and is now working in a fertility clinic, perfecting techniques that could eventually be used in the cloning of humans.

The complexity of cloning experiments depends on the overall aims of the experiment and the type of source material from which the nucleic acids will be isolated for cloning. Thus a strategy to isolate and sequence a relatively small DNA fragment from E. Coli will be different than a strategy to produce a recombinant protein organism. (An Introduction to Genetic Engineering, Desmond S.T. Nicholl; 6.1) There is no single cloning strategy that will cover all of the cloning requirements.

One way to clone is by cloning from mRNA. This method converts mRNA to DNA (also called copy DNA or cDNA). It uses the enzyme reverse transcriptase to produce complementary DNA. However, there are a few problems with cloning from mRNA. One of them is that the synthesis of full-length cDNAs may be inefficient, particularly if the mRNA is relatively long. More recent methods can overcome this problem. Another method is cloning cDNA in plasmid vectors. Scientists prefer using the bacteriophage vector system, but plasmids are still often used when isolation of the desired cDNA sequence involves screening a small number of clones.

There are also many different methods used in cloning. Three of the main methods used in cloning are blunt-end ligation, linker molecules and homopolymer tailing. Blunt-end ligation is just what it sounds like. The molecules join together using DNA ligase. Linker molecules are self-complementary oligomers that contain a recognition sequence for a particular restriction enzyme. Homoploymer tailing is when enzyme terminal transferase is used to add homopolymers of dA, dT, dG, or dT to a DNA molecule.

Scientists made a number of advances in cloning in 1998. In December, biologists in Japan said they had used a cloning technique to produce eight identical calves from cells removed from an adult cow. In July, researchers at the University of Hawaii announced that they had created more than 50 mice through cloning by using cells from adult mice. An apparent advance on the Roslin technique was reported in August 1997, when scientists at ABS Global Incorporated in DeForest, Wisconsin, a biotechnology company specializing in livestock reproductive services, said that they had produced