DNA
From RationalWiki
DNA is an organic nucleic acid that exists in all cells. It is composed of three basic components wrapped into a double helix structure, a phosphate group, a five-carbon sugar, and nitrogen bases. The phosphate and sugar (in this case, deoxyribose), exist act as the walls of the helix while genetic is information is stored in the sequence of nitrogen bases that connect the two sides of the helix. There are four basic nitrogen bases in DNA: Adenine, Cytosine, Guanine, and Thymine. Adenine can only bind with Thymine, and Guanine can only bind with cytosine (put simply, A and T, C and G). Although a limited code, massive strands of nitrogen bases can carry vast amounts of information, primarily used for the construction of proteins.
A considerable proportion of the cell's DNA is so-called "junk" DNA as it does not appear to have any specific purpose. As the exact way in which DNA is interpreted is not resolved, it is quite possible that some junk DNA performs a vital role.
[edit] Human DNA
The fact that no two people (except identical twins) have the same DNA allows determination of identity with a certainty of up to one in billions, although there have been cases where a shorter version of comparison testing has been used, and confusion has arisen.
Similarly, DNA can be used to determine ancestry, especially in cases where paternity has to be ascertained.
Mitochondrial DNA (which is only passed down the female line as mitochondria in the sperm are lost with the flagellum or selectively destroyed after fertilisation[1]) is used to study human evolution because it changes more slowly than cellular DNA. It has been used to trace the origin of female humans back to prehistoric Africa. Mitochondrial DNA is also used to trace the migration of humans after they left Africa.
Even Jesus had DNA, which was 99% similar to that of a chimpanzee.
