Thursday, July 03, 2008

Biomechanics


The world inside living cells is very mechanical--Michael Behe and other proponentsists of Intelligent Cdesign have told us so. Cells contain factories; I guess they are where the cells build motors.

The most common cellular motor is the Teeny-weeny Evinrude (Evinrudus microcephalicus), but this is by no means the only motor. A while back I posted a note about an itty-bitty Yamaha, an irreducibly complex machine whose complexity was reduced by its lack of an axle.

Those two cellular motors are just fine for operation in watery environments, but in dry territories motors need a means of taking up a load gradually, otherwise they will stall out. That's why we design automobiles with clutches (those with automatic transmissions utilize a fluid coupling which accomplishes the same result).

And so it is that the researchers of Intelligent Design will surely wet their pants when they hear about the wee clutches that are used to disengage the flagella in the soil bacterium Bacillus subtilis. A report (subscription req'd) by K.M. Bair and others in Science for 20 June 2008 describes how a group at Indiana University (yay!) put some bacterial cells on a real small hydraulic lift, pulled off the drive shaft and transmission, and fiddled with the clutch to see how it works. They found
The bacterial flagellum, powered by a motor that generates 1400 pN-nm of torque, can rotate at a frequency of greater than 100 Hz. EpsE [a gene that was mutated for this study--Mark] disabled this powerful biological motor when associated with a flagellar basal body and, in a manner similar to that of a clutch, disengaged the drive train from the power source.
The illustration at the top of this post is not from Blair &al.'s report. I used this one because it more clearly shows the important elements of a clutch, and the figures in the report just looked like a bunch of coiled ribbons with some colored balls. It's important in explaining Intelligent Design that you have pictures that clearly show the point you wish to make. If I had a properly-equipped garage, I would investigate the effect of installing tuned headers on bacteria.

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