What is cloning?

Cloning is the artificial and asexual production of cells or individuals that are genetically identical to other cells or individuals that already exist. There are three types: 1) reproductive cloning, which produces an entirely new and genetically-identical organism; 2) therapeutic cloning, which aims at producing cloned organs; 3) cellular cloning, which produces new cells to replace others.

There are different methods of cloning. The most important, for its impact on human cloning, is through the transfer of a nucleus. The method involves the extraction of an unfertilised egg from the womb, substituting the nucleus of another cell for the nucleus of that egg. The other cell comes from the organism that is to be ‘cloned’.

The famous case was that of Dolly the sheep in 1997. An unfertilised egg was taken from a sheep of the Blackface breed. That egg had its nucleus removed and another nucleus, taken from a cell of a sheep of the Finn Dorset breed, was inserted in its place. The clone was placed in the womb of a third sheep, also of the Blackface variety. It grew into the sheep that became known as Dolly. Since the nucleus of a somatic cell contains all the genetic information of the entire organism, the resultant “clone” contains that same information and so is, genetically speaking, identical with the cell that produced it. Dolly, who came from an egg of the Blackface breed, was herself a sheep of the Finn Dorset breed, since the new nucleus came from a Finn Dorset cell. She was genetically identical to the Finn Dorset sheep that gave its original nucleus.