Реферат на тему Cloning Essay Research Paper Of all the
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Cloning Essay, Research Paper
Of all the terms coined by scientists which have entered popular vocabulary, ‘clone’ has become one of the more emotive. Strictly speaking a clone refers to one or more offspring derived from a single ancestor, whose genetic composition is identical to that of the ancestor. No sex is involved in the production of clones, and since sex is the normal means by which new genetic material is introduced during procreation, clones have no choice but to have the same genes as their single parent. In the same way, a clone of cells refers simply to the descendants of a single parental cell. As such, adult organisms can be viewed as clones because all their parts stem from the single cell which is the fertilised egg. Likewise, many tumours are clones, derived from one aberrant cell which no longer obeys the normal rules of growth control. The offspring of organisms which reproduce asexually, like corals, are also clones; as are identical twins produced by the natural, or sometimes deliberate, splitting of a single embryo. Members of a clone are genetically identical and genetic identity has given cloning an additional more technical meaning: namely the procedures used to create a new organism whose genetic constitution is a replica of another existing individual. Such a feat can be achieved by substituting the nucleus, which contains the genes, from one of the cells making up that individual’s body, for the nucleus of a fertilised egg.