No layman's discussion about mitochondria is complete without the In Our Time episode on just that:
https://www.bbc.co.uk/programmes/m001md34
It is one of my favourites.
Previously posted: https://news.ycombinator.com/item?id=44051652 (1 day ago, 78 comments)
Can the entries be merged?
Can they? Yes. Should they? No.
Why have two separate discussions on the same topic a day apart?
What is the typical lifespan of ATP within a cell?
Are we talking milliseconds or minutes?
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.
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.
Wouldn't mind some bird mitochondria!
Seriously, what would happen if we swapped out human mitochondria from a zygote for bird mitochondria?
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.
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.
Well what if you also swapped out those genes?
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.
You'd get Kids in the Hall Chicken Lady.
And some whale blood!
vaguely related there is a fantastic new PBS Space Time this week which suggests the "no alien life" fermi paradox may be related to how our mitochondria evolved by a series of fortunate accidents which may not be reproducible elsewhere
https://www.pbs.org/video/is-there-a-simple-solution-to-the-...