[Bonjour]

If mitochondrial DNA is only inherited from the mother (as the sperm cell's mitochondria is in its tail which does not fuse with the egg cell at fertilisation) does that mean that everyone's mitochondrial DNA is exactly the same? And the same as the first woman that ever existed?

[Enigma.]

Well I'm not a genetics expert but I know a little bit about mitochondrial DNA from A level Bio. Enough to make an educated guess.

First, if there was only 1 woman who started the human race then yes we'd all have identical mitochondrial DNA (aside from mutations from things like radiation over the years.) But there wasn't. That's creationism. Which is totally untrue in the real world.

There is a theory that our mitochondria are present from a symbiosis between ancient bacteria and cells. A sort of fusion that benefits both. And we didn't all get mitochondria from one single bacterial cell.

So no, we don't all have the same mitochondrial DNA. Otherwise any disease caused by mitochondrial genetics would be present in every human on earth.

[Bonjour]

Ohh I see...so people within the same family would all have the same mitochondrial DNA

[Enigma.]

(Original post by Bonjour)
Ohh I see...so people within the same family would all have the same mitochondrial DNA

Well if its a mitochondrial disease then the mother would pass it on to all of her children because all of the children have her mitochondria.

The father could be affected or unaffected, depending on his parents.

So in a way, yes

[Bonjour]

Cool.. thanks lol :]

[Democracy]

(Original post by Bonjour)
If mitochondrial DNA is only inherited from the mother (as the sperm cell's mitochondria is in its tail which does not fuse with the egg cell at fertilisation) does that mean that everyone's mitochondrial DNA is exactly the same? And the same as the first woman that ever existed?

Not quite, however this may be of interest:

http://en.wikipedia.org/wiki/Mitochondrial_Eve