5 ms·
How does the body figure out which side is left and which side is right? I can think of an easy way to break symmetry but it seems harder to consistently know w
by changoplatanero 7y ago
How does the body figure out which side is left and which side is right? I can think of an easy way to break symmetry but it seems harder to consistently know which side is which.
- gus_massa 7y agoApparently it's not easy: https://en.wikipedia.org/wiki/Left-right_asymmetry_(biology) https://en.wikipedia.org/wiki/Left-right_asymmetry_(biology)
- dnautics 7y agoShort answer: at the single cell stage there's a cilium that, spins in a single direction and establishes chirality. People with immotile cilia thus have a 50/50 chance of getting SI, because the developing body chooses randomly.
- foobarbecue 7y ago!!!!!!!
- twic 7y agoI thought it was multiple cilia, wafting fluid in a current around a cavity, a bit later than the single cell stage but still very early? Either way, the reason a cilium spins in one direction rather than another is that the motor is a molecular machine built out of amino acids, and amino acids are themselves chiral. If you made a person out of amino acids with the opposite chirality, their cilia would go the other way, and their body would be flipped. It's a lovely example of magnifying something up from the molecular to the macroscopic.
- dnautics 7y agoThe motion of the cilia is not directly coupled to the chirality of the amino acids, you could probably make a cilium that obligatorily moved in the other direction with a handful of mutations.
- ambrop7 7y agoMaybe it figures out left/right but mixes up up/down :) Flipped upside down and rotated 180 degrees is the same thing as flipped left/right.