Cloning: Creating Genetically Identical Copies of Biological Matter

Cloning is the process of creating genetically identical copies of biological matter. This may include genes, cells, tissues or entire organisms. To Human Genome Project researchers, cloning refers to copying genes and other pieces of chromosomes to generate enough identical material for further study. Two other types of cloning produce complete, genetically identical animals.

Blastomere separation (sometimes called "twinning" after the naturally occurring process that creates identical twins) involves splitting a developing embryo soon after fertilization of the egg by a sperm (sexual reproduction) to give rise to two or more embryos.

The resulting organisms are identical twins (clones) containing DNA from both the mother and the father.

Dolly, on the other hand, is the result of another type of cloning that produces an animal carrying the DNA of only one parent. Using somatic cell nuclear transfer, scientists transferred genetic material from the nucleus of an adult sheep's udder cell to an egg whose nucleus, and thus its genetic material, had been removed. (All cells that are not egg or sperm cells are somatic cells.)

Cloning "Inventors"

Cloning has its beginnings in 1885, when Hans Adolf Edward Dreisch successfully "twinned" an artificial embryo using a sea urchin, a relatively simple organism. Dreisch showed that by shaking two-celled sea urchin embryos, he could separate the cells. Once separated, each cell grew into a complete sea urchin. This experiment showed that each cell in the early embryo has its own complete set of genetic instructions and can grow into a full organism.

In 1902, Hans Spemann completed artificial embryo twinning in a vertebrate (a salamander). First, he needed to determine how to split the two cells of an embryo that were much stickier than sea urchin cells. Spemann made a tiny "noose" from a strand of baby hair and tightened it between two cells of a salamander embryo until they separated.

Each cell grew into an adult salamander. This experiment showed that embryos from a more-complex animal can also be “twinned” to form multiple identical organisms—but only up to a certain stage in development.

In 1952, the first successful nuclear transfer occurred using frogs thanks to Robert Briggs and Thomas King. The pair transferred the nucleus from an early tadpole embryo into an enucleated frog egg (a frog egg from which the nucleus had been removed). The resulting cell developed into a tadpole. Briggs and King created many normal tadpole clones using nuclei from early embryos. Most importantly, this experiment showed that nuclear transfer was a viable cloning technique.

The First Cloning Company

CLONAID™ was founded in February 1997 by Raël who is the leader of the Raelian Movement, an international religious organization which claims that life on Earth was created scientifically through DNA and genetic engineering by a human extraterrestrial race whose name, Elohim, is found in the Hebrew Bible and was mistranslated by the word "God". The Raelian Movement also claims that Jesus was resurrected through an advanced cloning technique performed by the Elohim.


Genetic Science Learning Center. University of Utah.