Реферат: Cloning Animals Essay Research Paper

Cloning Animals Essay, Research Paper

 The cloning of animals will be beneficial to human beings inthe near future. Experiments in cloning animals started in theearly nine-teen-fifties. Over the next forty years, scientistswere only able to clone animals from very young embryonic cells. When these scientists tried to use older cells for cloning, theydid not get normal results. This led many scientists to believethat animals could not be cloned from adult cells. (Pennisi, 1997) However, this all changed in the Summer of 1995 with the birth oftwo lambs, Megan and Morag, at the Roslin Institute in Scotland. The birth of these two lambs led to one of the most astoundingbreakthroughs in scientific history, the birth of a lamb namedDolly. Megan and Morag were two lambs carried to term by a surrogatemother. However, Megan and Morag were not produced by normalbiological methods. Their genetic code came from the cells of anine-day-year old embryo. Thus, Megan and Morag were geneticcopies, or clones of this embryo. The key to this cloning was aprocess called nuclear transfer. This process requires the use oftwo cells, the donor cell and the recipient cell. The recipientcell is usually an unfertilized egg. Researchers at the RoslinInstitute used microscopic instruments, like a micro pipette, toextract all of the chromosomes from the recipient cell. Therecipient cell was then fused to the donor cell and placed into thesurrogate mother. The birth of Megan and Morag was a tremendousbreakthrough because these scientists proved that older cells couldbe genetically reprogrammed to act like cells in an early embryonicstage. (Wilmut, 1998) The research that went into the development of Megan and Morageventually led to the birth of the first mammal cloned from anadult mammal. To accomplish this, the research team at the Roslininstitute used cells removed from a six-year-old ewe s udder. These cells were then deprived of any nutrition, which forced thegenes to become inactive. The researchers did this because theywanted the cell-cycle stage of the recipient to be the same as thedonor s cell-cycle stage. The researchers then performed thenuclear transfer and tried to stimulate the inactivated genes tostart to develop into a new lamb. Only one out of two-hundred and

seventy-seven eggs produced a healthy lamb, which was named Dolly. The difference between the cloning of Megan and Morag and thecloning of Dolly is that Megan and Morag were cloned from a youngcell, while Dolly was cloned from an adult cell. This was thefirst time that an animal had ever been cloned from and adult cell. Thus, proving the theory, that an animal could not be cloned froman adult cell, was wrong. (Pennisi, 1997) The birth of Dolly, which was in February of 1997, has led toincreased research and development into the cloning of animals. OnWednesday, the eighth, the Washington Post printed an article whichstated that Japanese researchers had cloned eight calves from oneadult cow. This achievement is a big improvement over Dollybecause eight calves were born from ten attempts, while Dolly wasthe only successful birth out of two-hundred and seventy-seveneggs. These calves were cloned from cells taken form a cow sovaries and fallopian tubes. The cells that were taken from thefallopian tubes were a kind of cell that had never been used forcloning before. The cloning of these calves is big news becausecows are one of the most commercially important animals. Thecloning of cows will allow for an easier way of expanding the herdsand developing cows to produce more and better milk. (Weiss, 1998) The cloning of animals will be a very important part of ourfuture, especially the animals that we rely on. One way thatcloning animals will be important to us is that only the best ofeach type of animal that we rely on, like cows that produce qualitybeef and milk, would be cloned. Thus reducing the possibility ofdisease carried in these animals, like mad cow disease. A secondway that cloning would be beneficial to us, is that once scientistsfigure out how to add other beneficial characteristics to a donorcell, then animals could be genetically engineered to be resistantto all forms of disease. These animals could also be engineered tobe able to donate organs to humans. In the case of cows, theycould be developed to produce medicines in their milk that would bebeneficial to humans. Researchers at the Roslin institute arealready working on cloning sheep with a gene that would allow thesheep to produce milk that contains a beneficial protein thathemophiliacs use to aid in allowing their blood to clot. (Pennisi,1997)

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