clone (redirected from clones)

clone, group of organisms, all of which are descended from a single individual through asexual reproduction, as in a pure cell culture of bacteria. Except for changes in the hereditary material that come about by mutation, all members of a clone are genetically identical. Laboratory experiments in in vitro fertilization of human eggs led in 1993 to the "cloning" of human embryos by dividing such fertilized eggs at a very early stage of development, but this technique actually produces a twin rather than a clone. In a true mammalian clone the nucleus from a body cell of an animal is inserted into an egg, which then develops into an individual that is genetically identical to the original animal.

Later experiments in cloning resulted in the development of a sheep from a cell of an adult ewe (in Scotland, in 1996), and since then rodents, cattle, swine, and other animals have also been cloned from adult animals. Despite these trumpeted successes, producing cloned mammals is enormously difficult, with most attempts ending in failure; cloning succeeds 4% or less of the time in the species that have been successfully cloned. In addition, some studies have indicated that cloned animals are less healthy than normally reproduced animals.

In 2001 researchers in Massachusetts announced that they were trying to clone humans in an attempt to extract stem cells. The National Academy of Sciences, while supporting (2001) such so-called therapeutic or research cloning, has opposed (2002) the cloning of humans for reproductive purposes, deeming it unsafe, but many ethicists, religious and political leaders, and others have called for banning human cloning for any purpose. South Korean scientists announced in 2004 that they had cloned 30 human embryos, but an investigation in 2005 determined that the data had been fabricated.

Bibliography

See G. Kolata, Clone (1997).

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clone

Population of genetically identical cells or organisms that originated from a single cell or organism by nonsexual methods. Cloning is fundamental to most living things, since the body cells of plants and animals are clones that come ultimately from a single fertilized egg. More narrowly, the term refers to an individual organism grown from a single body cell of its parent that is genetically identical to the parent. Cloning has been commonplace in horticulture since ancient times; many varieties of plants are cloned simply by obtaining cuttings of their leaves, stems, or roots and replanting them. The body cells of adult humans and other animals are routinely cultured as clones in the laboratory. Entire frogs and mice have been successfully cloned from embryonic cells. British researchers led by Ian Wilmut achieved the first success in cloning an adult mammal in 1996. Having already produced clones from sheep embryos, they were able to produce a lamb (Dolly) using DNA from an adult sheep. The practical applications of cloning are economically promising but philosophically unsettling.

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clone

A product that functions like another. The clone, which may be hardware, software or both, may not look exactly like the original, but it implies 100% functional compatibility with it. Fed the same input, the clone should produce the same output. See PC clone, white box, clean room technique and cloning software.

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clone

1. Biology a group of organisms or cells of the same genetic constitution that are descended from a common ancestor by asexual reproduction, as by cuttings, grafting, etc., in plants

2. a segment of DNA that has been isolated and replicated by laboratory manipulation: used to analyse genes and manufacture their products (proteins)

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(jargon)

clone - 1. An exact copy of a product, made legally or illegally, from documentation or by reverse engineering, and usually cheaper. E.g. "PC clone": a PC-BUS/ISA, EISA, VESA, or PCI compatible x86-based microcomputer (this use is sometimes misspelled "klone" or "PClone"). These invariably have much more bang per buck than the IB PCM they resemble. E.g. "Unix clone": An operating system designed to deliver a Unix-like environment without Unix licence fees or with additional "mission-critical" features such as support for real-time programming. 2. A clonebot.