Left-right asymmetry

[mmcirvin]

I 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.

Comments

[iayork.livejournal.com]

I like cool biology articles because I really understand this stuff so poorly

Heh. This morning I had a consultation with a statistician, about a problem I'm working on related to how particularly antigenic epitopes are generated from the background of all cellular proteins. The consultant turned out to be a PhD candidate in the math department; a very nice lady, but completely, and I mean cmopletely, blank on biology. I mean, I started to give a brief explanation of the problem -- three words in, I said "amino acids" and a look of utter panic crossed her face. So I dropped down about five levels of complexity, and she seemed to sort of flounder along. Eventually I got to the part where I had a 20x15 table of frequencies to compare to background frequencies and she sighed with relief, drew a deep beath, and started muttering about regressions.

[mmcirvin.livejournal.com]

I just had to look up the word "epitope" to follow that, but otherwise I could...

In the process I discovered that "racemic" comes from a term meaning "from grape juice".

[mmcirvin.livejournal.com]

...I have a layman's interest in most fields of science, but I've always been acutely conscious of the fact that, for a variety of reasons, the last actual biology course I ever took was a high-school introductory course taught by a man who had primarily been hired as an athletic coach and was fairly ignorant (his other major task was doing the morning PA announcements; I recall partiallyclips could do a really good impression of him).