Reproductive cloning uses "somatic cell nuclear transfer" (SCNT) to create animals that are genetically identical. This process entails the transfer of a nucleus from a donor adult cell
to an egg which has no nucleus. If the egg begins to divide normally it is transferred into the uterus of the surrogate mother.
Such clones are not strictly identical since the somatic cells may contain mutations in their nuclear DNA. Additionally, the mitochondria in the cytoplasm also contains DNA and during SCNT this DNA
is wholly from the donor egg, thus the mitochondrial genome is not the same as that of the nucleus donor cell from which it was produced. This may have important implications for cross-species nuclear
transfer in which nuclear-mitochondrial incompatibilities may lead to death. |