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CLONING - Discusion

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Introduction

CLONING The possibility of human cloning, raised when Scottish scientists at Roslin Institute created the much-celebrated sheep "Dolly", created worldwide interest and concern because of its scientific and ethical implications. The feat, cited by Science magazine as the breakthrough of 1997, also generated uncertainty over the meaning of "cloning" a term traditionally used by scientists to describe different processes for duplicating biological material. When the media report on cloning in the news, they are usually talking about only one type called reproductive cloning. There are different types of cloning however, and cloning technologies can be used for other purposes besides producing the genetic twin of another organism. A basic understanding of the different types of cloning is important to taking an informed stance on current public policy issues and making the best possible personal decisions. The following three types of cloning technologies will be discussed: a) recombinant DNA technology or DNA cloning, b) ...read more.

Middle

coli cells. BACs utilize the naturally occurring F-factor plasmid found in E. coli to carry 100 to 300 kb DNA inserts. A YAC is a functional chromosome derived from yeast that can carry up to 1 MB of foreign DNA. Bacteria are most often used as the host cells for recombinant DNA molecules, but yeast and mammalian cells also are used. Reproductive cloning is a technology used to generate an animal that has the same nuclear DNA as another currently or previously existing animal. Dolly was created by reproductive cloning technology. In a process called "somatic cell nuclear transfer" (SCNT), scientists transfer genetic material from the nucleus of a donor adult cell to an egg whose nucleus, and thus its genetic material, has been removed. The reconstructed egg containing the DNA from a donor cell must be treated with chemicals or electric current in order to stimulate cell division. Once the cloned embryo reaches a suitable stage, it is transferred to the uterus of a female host where it continues to develop until birth. ...read more.

Conclusion

Stem cells are extracted from the egg after it has divided for 5 days. The egg at this stage of development is called a blastocyst. The extraction process destroys the embryo, which raises a variety of ethical concerns. Many researchers hope that one day stem cells can be used to serve as replacement cells to treat heart disease, Alzheimer's, cancer, and other diseases. In November 2001, scientists from Advanced Cell Technologies (ACT), a biotechnology company in Massachusetts, announced that they had cloned the first human embryos for the purpose of advancing therapeutic research. To do this, they collected eggs from women's ovaries and then removed the genetic material from these eggs with a needle less than 2/10,000th of an inch wide. A skin cell was inserted inside the enucleated egg to serve as a new nucleus. The egg began to divide after it was stimulated with a chemical called ionomycin. The results were limited in success. Although this process was carried out with eight eggs, only three began dividing, and only one was able to divide into six cells before stopping. ...read more.

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