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ClarkFable t1_iraw6hc wrote

but that mitochondrial DNA is printed from some subset of the 46 chromosomes as everything else, so what's the distinction? i.e., humans start as a zygote, not a zygote + some mitochondrial DNA, right?


kanated t1_ircm4po wrote

>that mitochondrial DNA is printed from some subset of the 46 chromosomes

It's not.

Don't think of mitochondria as just another organelle. Think of them as something similar to a parasite that lives inside your cells, except it's beneficial.

They have their own DNA, they reproduce independently. They aren't formed in the zygote, they already come inside the egg. They spread from mother to child this way for billions of years. Each time a cell divides, some of them go along.


rintryp t1_irb6e17 wrote

Actually the mitochondria are a given from the mother, so the egg already has mitochondria whereas semen only brings in some nucleus DNA but no mitochondria.


Arcal t1_irbmw53 wrote

Mitochondria have their own chromosomes, tens to thousands of copies per cell. Your mother's egg cell had its own mitochondria with its own DNA. That's what all your mitochondria have now. Somehow, the mitochondria from sperm are specifically targeted and eliminated. We're still working on that mechanism.


TheGreat_War_Machine t1_irchier wrote

Sperm don't have mitochondria in the first place, do they not?


Arcal t1_irckqk1 wrote

They do, hard working ones too, for all that swimming.