twins

Tom Matthews tmatth at netcom.ca
Fri Feb 20 19:43:59 EST 1998


Ron Apland wrote:
> 
> > <snip>
> >>Even identical twins, however, are of at least two kinds. All share
> >>original nuclear DNA, but some may have different mitochondrial DNA.
> > <snip>
> >
> >       Forgive my ignorance, but pray tell how identical twins may
> > possess different mitochondrial genomes?
> 
> Ditto for me. Does not the molecular clock method of tracing human
> ancestry depend on mitochondrial DNA? If cells of a person
> have different mitochondrial DNA or mitochondria within a cell have
> different DNA then how is this molecular clock calculated?

I understand this and I know that human mtDNA is very efficient with no
excess "baggage". However, there are specific diseases caused by
mitochondrial alleles. So I thought there might possibly be *some*
alleles which are not fatal and get propagated. And furthermore, that
mitochrondria with two such different alleles might be able to end up
within the cells of the same individual. Certainly, any differences in
human mtDNA would not be large compared with, say, the differences
between human and chimpanzee mtDNA.

--Tom 
Tom Matthews
 
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