Cloning

Cloning is the process of producing individual organisms with identical genomes, by either natural or artificial means. In nature, some organisms produce clones through asexual reproduction; this reproduction of an organism by itself without a mate is known as parthenogenesis. In the field of biotechnology, cloning is the process of creating cloned organisms of cells and of DNA fragments. The artificial cloning of organisms, sometimes known as reproductive cloning, is often accomplished via somatic-cell nuclear transfer (SCNT), a cloning method in which a viable embryo is created from a somatic cell and an egg cell. In 1996, Dolly the sheep achieved notoriety for being the first mammal cloned from an adult somatic cell. Another example of artificial cloning is molecular cloning, a technique in molecular biology in which a single living cell is used to clone a large population of cells that contain identical DNA molecules. In bioethics, there are a variety of ethical positions regarding the practice and possibilities of cloning. The use of embryonic stem cells, which can be produced through SCNT, in some stem cell research has attracted controversy. Cloning has been proposed as a means of reviving extinct species. In popular culture, the concept of cloning—particularly human cloning—is often depicted in science fiction; depictions commonly involve themes related to identity, the recreation of historical figures or extinct species, or cloning for exploitation (e.g. cloning soldiers for warfare).