In a message dated 7/21/01 3:30:27 AM Pacific Daylight Time, email@example.com
> Are their mitochondria different? I would think that their higher
> metabolic rate is due to more mitochondria rather than more efficient
> mitochondria. Anybody who knows, my animal physiology textbooks didn't
> give a clear answer.
Generically, warm-blooded mammals don't differ too
much in mitochondrial efficiency; they all operate
at obscenely low oxygen tensions (try 5% of atmospheric)
Differences in throughput result from differences in
oxygen delivery; for example, birds have this nifty
lung system which separates incoming from outgoing
air so the first part of a breath isn't used air.
Well, nifty for oxygen transport; seems to make them
more susceptible to pulmonary infections.
Mitochondria differ a lot in their ability to manage
free radicals but those abilities are encoded in
the nucleus and transported to the mitochondria.
It's an excellent bet that bird or bats have such
secondary enzymes that would really help us. We'd
need to engineer our nuclei though; xplanting the
mitochondria wouldn't help. Bats would likely be
a better source than birds since they're more closely
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