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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. In 1962 John Gurdon was the first to clone an animal when he transferred cell nuclei from adult frog intestinal cells and injected them into egg cells from which the nucleus had been removed; the eggs then developed into tadpoles. 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 (as in Gurdon's frog 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 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.
In 2013 scientists at Oregon Health and Science Univ. reported that they had created embryonic stem cells using genetic material from human skin cells and donated eggs; the technique used to create the embryo, however, would not result in a viable human clone. The Oregon team had done similar work in several years before with monkeys. The cloning of two monkeys that was reported in 2017 by researchers at the Chinese Academy of Science, Shanghai, did not use DNA from adult cells but from an aborted macaque fetus.
See G. Kolata, Clone (1997).
several successive generations of hereditarily similar organisms (or individual cells in cultures), formed as a result of asexual or vegetative reproduction from a common ancestor.
Isolating a clone is one of several ways of obtaining genotypically uniform material. However, because of possible mutations, the genotypic homogeneity of a clone is relative. The varieties of plants cultivated vegetatively (for example, the potato) are often individual clones.
In microbiology and protistology, a clone is the set of progeny of a single parental cell.
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. <chat> A clonebot.
clone(1) To make an identical copy of something. See cloning software.
(2) 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 and clean room technique.