cloning

A living system that is genetically identical to its ancestor (that is, it has exactly the same DNA molecules). Because each cell contains the DNA molecules that characterize an individual, it is, in principle, possible to replicate, or reproduce, complex living systems in the laboratory.

Note: The first cloned mammal, a sheep named Dolly, was born in Scotland in 1996. DNA from an adult donor was placed into an egg, which was then implanted in the uterus of another sheep. Since that time, mice, cows, and pigs have been cloned.

Note: There is a major debate on the ethical aspects (see bioethics) of cloning, especially as applied to human beings. Therapeutic cloning involves the placing of adult DNA in an egg for the express purpose of creating stem cells for medical purposes. Reproductive cloning involves the placement of adult DNA into an egg and the implantation of the egg into a uterus for the purpose of creating a viable fetus.

Note: Clone is often used informally to indicate a close copy or resemblance: “This new computer is a clone of the IBM model.”

clone (klōn)
n.

1. A group of genetically identical cells descended from a single common ancestor, such as a bacterial colony whose members arose from a single original cell as a result of binary fission.

2. An organism descended asexually from a single ancestor, such as a plant produced by layering or a polyp produced by budding.

3. A replica of a DNA sequence, such as a gene, produced by genetic engineering.

1. To make multiple identical copies of a DNA sequence.

2. To establish and maintain pure lineages of a cell under laboratory conditions.

3. To reproduce or propagate asexually.