Klon

Klon is a term in biology that refers to a genetically identical copy of an organism or cell. Clones can arise naturally, for example when bacteria reproduce by binary fission or when plants form new individuals from cuttings. The word clone derives from the Greek klōn, meaning twig or sprout, and was coined by the American botanist Herbert Copeland in 1903.

Cloning covers several processes. DNA cloning, or gene cloning, copies a particular DNA fragment for research, medical use, or biotechnology. Reproductive cloning creates a whole organism that is genetically identical to its donor. Therapeutic cloning aims to produce cells or tissues for treatment rather than a complete individual.

Common methods include somatic cell nuclear transfer (SCNT), where the nucleus of a donor cell is transferred into an enucleated egg cell, and embryo splitting, which produces genetically identical individuals from a single early embryo. In addition, genetic engineering in bacteria or yeast can replicate specific DNA sequences to identical copies.

Notable milestones include Dolly the sheep (1996), the first mammal cloned from an adult somatic cell using SCNT. Since then, various animals have been cloned, including cattle, cats, and dogs. Human reproductive cloning remains prohibited or tightly regulated in most countries, while therapeutic cloning remains controversial and regulated in many jurisdictions.

Key considerations include that clones are genetically identical to their donor at the DNA level, but epigenetic differences and environmental factors can lead to phenotypic variation. Cloning efficiency is often low, and cloned animals may exhibit health problems or reduced lifespans.

Applications span agriculture, medicine, and biotechnology, supporting research into gene function, development, and the production of cells, tissues, or organoids for therapy or study. Ethical, legal, and social debates focus on safety, animal welfare, identity, and potential human cloning.