[BobS]

"Aren't there only something like 7 mitochondria lines in the world?"

I vaguely remember that mitochondria determines female heritage. RNA? Do they supply the ribonucleic part for the DNA in the master chromosomes? Darn. This is not my field because it takes less time to follow engineering than cell biology. Let the experts define the answer.

[Paleo Conservative]

I vaguely remember that mitochondria determines female heritage. RNA? Do they supply the ribonucleic part for the DNA in the master chromosomes?

No. The mitochondrial DNA is totally separate from the nuclear DNA. It is believed that mitochondria are decended from formerly free living bacteria that entered into an intracellular symbiotic relationship with the ancestors of eucaryotic organisms billions of years ago.