Sunday, February 3, 2013

"Mitochondrial Eve" (1)

We will condense Fairbanks presentation, not to obscure it,
nor only to avoid copyright, (it would be unfair use to quote all 124 pages),
but also to make it even clearer to readers:

Regular (Chromosome) DNA, and Mitochondrial DNA (mtDNA)

DNA is actually found in two places within human cells:

(1) The nucleus holds most of our DNA.

(2)  Another smaller amount of our DNA is stored and used in mitochondria.


The mitochondria are small factories in our cells, outside the nucleus.
A cell has about 100 mitochondria inside it.
Each mitochondria has between 1 and 15 extra DNA-rings, typically about 5.
Each mitochondrial DNA-ring has normally 16,569 DNA base pairs.


Obviously this extra DNA is stored differently, copied differently, and transmitted differently to other cells and offspring.


During Sexual Reproduction (in humans),
the male sperm only carries a copy of the Nuclear DNA.
The male's mitochondrial DNA (mtDNA) is left behind.

The mtDNA is supplied in the egg from the mother,
because her egg comes already all the mitochondria pre-formed.

Thus while the male contributes only to the Nuclear DNA (chromosomes),
the female supplies the small amount of mitochondrial DNA (mtDNA).

As a result, inheritance of mtDNA is traced back through the female line.


However, mitochondrial DNA (called mtDNA) is not 'independent', and mitochondria are spawned, regulated, modified and passed on under the control of the main
Nuclear DNA (our chromosomes).   They are an integral part of the cell structure,
and fully integrated in every working living cell.

When mitochondria and their own DNA is passed on, this is done
under the direction of the Nuclear DNA, our chromosomes.
Even sexual reproduction (as opposed to simple cell division)
is directed under the control of our chromosomes.

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