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Left-right asymmetry
Aug. 30th, 2006 06:36 pmI like cool biology articles because I really understand this stuff so poorly; I'm almost guaranteed to learn something new. Here, PZ Myers tells us how cilia that rotate clockwise end up nudging early embryonic development in such a way as to generate the usually consistent left-right asymmetry that exists in our bodies. As commenter Rosie Redfield points out, the direction in which the cilia rotate is in turn determined by the handedness of our proteins, so it all comes down to a molecular asymmetry going back to the beginning of life.
I know that physicists have often wondered whether the handedness of protein helices in living organisms is something that was just randomly picked out and amplified by early organisms, or if there's some fundamental physical basis for it, maybe involving parity-violating weak interactions. I'd say "just random" is probably the way to bet. But I'm not sure how it could be known for sure, absent finding life similar to ours elsewhere in the universe that has the other handedness in its proteins (and even that might not be entirely conclusive). Then again, there's this strange result from the Murchison meteorite.
I know that physicists have often wondered whether the handedness of protein helices in living organisms is something that was just randomly picked out and amplified by early organisms, or if there's some fundamental physical basis for it, maybe involving parity-violating weak interactions. I'd say "just random" is probably the way to bet. But I'm not sure how it could be known for sure, absent finding life similar to ours elsewhere in the universe that has the other handedness in its proteins (and even that might not be entirely conclusive). Then again, there's this strange result from the Murchison meteorite.
