Seriously, what would happen if we swapped out human mitochondria from a zygote for bird mitochondria?

And some whale blood!

Can the entries be merged?

According to the wikipedia page on ATP, the average ATP concentration in eukaryotic cells is 1 to 10 micromols per gram.

According to https://bionumbers.hms.harvard.edu/bionumber.aspx?s=n&v=2&id... a single mammalian cell has a mass of 3 to 4 nanograms.

Google AI tells me the average rate of ATP formation in a mammalian cell is around 10 million molecules per second.

The ratio here ranges from 3 to 40 minutes.

I imagine it varies greatly depending on cell type.

From an exercise physiology point of view, it's generally accepted that ATP-CP powered motility is possible for only about 10 seconds (that is to say, you only store enough ATP for about 10 seconds of high intensity work -- sprinting, maximal weight lifting, etc). After that, other energy systems become dominant ... both of which create ATP but depend on either glycolysis (anaerobic) or oxidative phosphorylation (aerobic) for the process/conversion.