Bacterial flagellum

Check the book again; if that is really what it says, then it is wrong. There are several different kinds of flagella in nature. The three major divisions are bacterial, archaeal (another sort-of bacteria) and eukaryotic (not bacteria, but cells with a nucleus).It is the eucaryotic flagella that beat; but both forms of bacterial flagella do indeed truly rotate.More information is available from wikipedia, and is also available in a number of discussions of flagella on-line.Cheers -- Sylas

Yes. It does rotate in its socket; no question. The rapid rotation of a long thread like object does cause it to whip about, especially in such small structures. The whipping effect induced by the rotation is what allows it to propell the bacterium.Cheers -- Sylas

My understanding is that it does spin the bacterium. I don't know that I'd call the motor "inefficient", however.The way in which direction is apparently achieved is inefficient, however. (Though I'd say it is remarkable efficiency to pack an effective motion system into such a tiny package!)My understanding is that bacteria usually spin for a short time, moving in a mostly straight line at signficant speeds. Then they stop, and have a short "tumble". Then they move off again, in a different completely random direction.So how do they get direction? Interestingly, it is by a kind of analog to selection and variation! Suppose, for example, that a bacterium tends to move towards a light source. The way this is acheived is by having the length of time of the straight line movement be related to the light intensity. In a dark place, they tend to move in straight lines for a longer time before entering the tumble mode. This increases the probability that they will move away from the dark.Cheers -- Sylas

( Duplicate post bug; apparently caused when I refreshed the response screen which had failed to load properly. }This message has been edited by Sylas, 05-20-2004 05:41 PM