I’m glad you didn’t write this review, now I got to instead :-)
I could be wrong and I would like to be corrected if I am. From your writings and from having met you, I would not be surprised if you know far more biology than I do.
(3) It follows from (1) + (2) that if there’s a big complicated cell doing lots of stuff, it needs a gazillion copies of its genome per cell;
Why can’t bacterium/archaeon just have many copies of the same ATP gene on a single genome? Duplicating a DNA segment is not an uncommon mutation.
On the other hand, packaging ATP genes in mitochondria lets a cell create more or less of them on demand, something it can’t do with a repeated sequence in DNA.
Can’t a bacteria increase the effective surface area by, say, putting ATP production machinery onto a vesicle?
If I understand correctly, mitochondria use cristae for this purpose instead of vesicles. Cristae are what gives mitochondria membranes their characteristic shape.
I think the “nearby” part is important … I thought his claim was basically that if I’m an ATP production machine, I need the genome to be really close to me distance-wise (like within X nanometers, for some number X that I don’t know), so that if I have a broken part then a replacement can be quickly manufactured on demand in the right location. So having 100 copies of the gene that are physically attached to each other doesn’t help at all towards solving the problem, and in fact makes the problem worse.
I really don’t know much biology, I’m just going off my memory of the book :-)
I’m glad you didn’t write this review, now I got to instead :-)
I could be wrong and I would like to be corrected if I am. From your writings and from having met you, I would not be surprised if you know far more biology than I do.
Why can’t bacterium/archaeon just have many copies of the same ATP gene on a single genome? Duplicating a DNA segment is not an uncommon mutation.
On the other hand, packaging ATP genes in mitochondria lets a cell create more or less of them on demand, something it can’t do with a repeated sequence in DNA.
If I understand correctly, mitochondria use cristae for this purpose instead of vesicles. Cristae are what gives mitochondria membranes their characteristic shape.
I think the “nearby” part is important … I thought his claim was basically that if I’m an ATP production machine, I need the genome to be really close to me distance-wise (like within X nanometers, for some number X that I don’t know), so that if I have a broken part then a replacement can be quickly manufactured on demand in the right location. So having 100 copies of the gene that are physically attached to each other doesn’t help at all towards solving the problem, and in fact makes the problem worse.
I really don’t know much biology, I’m just going off my memory of the book :-)
He definitely did say something to that effect and it definitely is easier to have the genome near the cell wall of a small cell than a large cell.
You say “the genome” but note that one bacterium (i.e. one cell) can have more than one copy of its entire genome inside it, e.g. “many bacteria harbor multiple copies of their genome per cell”, “Enormous bacterium uses thousands of genome copies to its advantage”, etc. That’s what I was (implicitly) referring to. :-)
I did not realize that. Whoops.