The term clone is derived from κλών, the Greek word for "trunk, branch", referring to the process whereby a new plant can be created from a twig. In horticulture, the spelling clon was used until the twentieth century; the final e came into use to indicate the vowel is a "long o" instead of a "short o". Since the term entered thepopular lexicon in a more general context, the spelling clone has been used exclusively.
There are many kinds of cloning :
* 1 Molecular cloning
* 2 Celular Cloning
* 3 Organism cloning
2.1 Horticultura and Parthenogenesis cloning
* 2.3 Artificial cloning of organisms
* 2.3.4 Human cloning
2.3.6 Cloning extinct and endangeredspecies
Cloning, or more precisely, the reconstruction of functional DNA from extinct species has, for decades, been a dream of some scientists. The possible implications of this were dramatized in the best-selling novel by Michael Crichton and high budget Hollywood thriller Jurassic Park. In real life, one of the most anticipated targets for cloning was once the Woolly Mammoth, but attempts toextract DNA from frozen mammoths have been unsuccessful, though a joint Russo-Japanese team is currently working toward this goal.
In 2001, a cow named Bessie gave birth to a cloned Asian gaur, an endangered species, but the calf died after two days. In 2003, a banteng was successfully cloned, followed by three African wildcats from a thawed frozen embryo. These successes provided hope thatsimilar techniques (using surrogate mothers of another species) might be used to clone extinct species. Anticipating this possibility, tissue samples from the last bucardo (Pyrenean Ibex) were frozen immediately after it died. Researchers are also considering cloning endangered species such as the giant panda, ocelot, and cheetah. The "Frozen Zoo" at the San Diego Zoo now stores frozen tissuefrom the world's rarest and most endangered species.
In 2002, geneticists at the Australian Museum announced that they had replicated DNA of the Thylacine (Tasmanian Tiger), extinct about 65 years previous, using polymerase chain reaction. However, on February 15, 2005 the museum announced that it was stopping the project after tests showed the specimens' DNA had been too badlydegraded by the (ethanol) preservative. Most recently, on May 15, 2005 it was announced that the Thylacine project would be revived, with new participation from researchers in New South Wales and Victoria.
One of the continuing obstacles in the attempt to clone extinct species is the need for nearly perfect DNA. Cloning from a single specimen could not create a viable breeding population in sexuallyreproducing animals. Furthermore, even if males and females were to be cloned, the question would remain open whether they would be viable at all in the absence of parents that could teach or show them their natural behavior. Essentially, if cloning an extinct species were successful — it must be considered that cloning is still an experimental technology that succeeds only by chance — it is morelikely than not that any resulting animals, even if they were healthy, would be little more than curios or museum pieces.
Cloning endangered species is a highly ideological issue. Many conservation biologists and environmentalists vehemently oppose cloning endangered species — mainly because they think it may deter donations to help preserve natural habitat and wild animal populations. The...