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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 mutationmutation,
in biology, a sudden, random change in a gene, or unit of hereditary material, that can alter an inheritable characteristic. Most mutations are not beneficial, since any change in the delicate balance of an organism having a high level of adaptation to its environment
..... Click the link for more information. , all members of a clone are genetically identical. In 1962 John GurdonGurdon, Sir John Bertrand,
1933–, British biologist, Ph.D. Oxford, 1962. He has been a researcher at Cambridge since 1971. Gurdon was the joint recipient of the 2012 Nobel Prize in Physiology or Medicine with Shinya Yamanaka for the discovery that mature cells can be
..... Click the link for more information. 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 fertilizationin vitro fertilization
(IVF), technique for conception of a human embryo outside the mother's body. Several ova, or eggs, are removed from the mother's body and placed in special laboratory culture dishes (Petri dishes); sperm from the father are then added, or in many cases a
..... Click the link for more information. 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 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 cellsstem cells,
unspecialized human or animal cells that can produce mature specialized body cells and at the same time replicate themselves. Embryonic stem cells are derived from a blastocyst (the blastula typical of placental mammals; see embryo), which is very young embryo that
..... Click the link for more information. . 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.
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.