[jyounker]

I don't think you'd get the same sort of effects, because a huge part of the mitochondrial regulation and function is carried out by genes and gene products from outside the mitochondria.

It would be an interesting experiment though. I'd expect that they might not live, or that the cell would function sub-optimally, but who knows, maybe the cellular machinery is highly conserved.

[dejj]

Yes. Afaik from Nick Lane’s “Oxygen” the Cytochrome Oxidase made from the mitochondrial DNA have to match the Cytochrome C made from nuclear DNA. Even slight mismatch seems to lower mitochondrial performance and is a problem why heteroplasmy (mixing of mitochondria from father and mother) seems to be selected-out.

[treyd]

Well what if you also swapped out those genes?

[dejj]

If your mitochondria have bird DNA and your nucleus has bird DNA, then you’re a bird.

There’s an easier way. A single nucleotide polymorphism (SNP) that only and rarely is observed in Japanese can extend human lifespan greatly. Flip a single base pair. This seems the most promising first step for genetically engineering humans.