The biological definition of a genetic cloning
The biological definition of a genetic cloning - …
One other potential source of differences among animals cloned from genetically identical nuclei is cytoplasmic (see Figure 1) inheritance, illustrated most clearly by mitochondria. Mitochondria are small cytoplasmic bodies located in all cells (with hundreds per cell). They have numerous functions, including generation of energy for such life processes as muscular movement. Mitochondria have their own genetic information in the form of small, circular chromosomes. These almost always are inherited exclusively from mother via the oocyte. Different maternal lines have mitochondria of different genetic makeup, so it is the cytoplasm of the oocyte that determines the makeup of the mitochondrial genome, rather than the chromosomes in the nucleus. Thus, when cloning by nuclear transfer, the mitochondrial genetics will differ from clone to clone unless the oocytes are all derived from the same maternal line of females.
A biological definition of cloning | Motaxis
Another source of differences among clones is mutations in the DNA in nuclear chromosomes or mitochondria. DNA is composed of only four kinds of building blocks, known as adenine, thymine, guanine, and cytosine, or A, T, G, and C, respectively. The genetic makeup (DNA) of the nucleus of each mammalian diploid cell has around 12 billion of these building blocks, theoretically hooked together in precisely the same way when DNA is replicated, so that each daughter cell produced has the same genetic makeup, or order of the four building blocks as the "parent" cell that divided. As one might imagine, there is an occasional error when assembling 12 billion items in a specific sequence, and these errors are one source of mutations. Other causes of mutations include background radiation (with which we are constantly bombarded) and chemical reactions, such as peroxidation, which is a chemical process caused by oxygen that can be very detrimental.