April 4, 2005 | David F. Coppedge

Flagellum Described in High-Performance Lingo

The bacterial flagellum, a virtual icon of the intelligent design movement, has been studied by many researchers, notably Howard Berg of Harvard, an expert on chemotaxis (the attraction of bacteria to chemical stimuli).  Berg was interviewed in Current Biology1 and talked like a race car mechanic when discussing this molecular machine, though he is not involved in the ID movement and believes in evolution.  Here are some excerpts:

  • The modern era [of chemotaxis studies] began in the 1960s with Tetsuo Iino and Sho Asakura in Mishima and Nagoya, who began work on the structure of flagellar filaments (thought then to be primitive bending machines)…
  • the flagellar motor has several pistons and a novel torque-speed relationship….
  • We hope to understand how bacterial chemotaxis works, every nut and bolt.  Who would have imagined: receptor complexes that count molecules and make temporal comparisons; activation of a diffusible signal that couples receptors to flagella; reversible rotary engines that drive propellers of variable pitch; force generators, rotors, drive shafts, bushings, and universal joints; a system with prodigious sensitivity, with amplification generated by receptor-receptor interactions?  The biggest black box is the motor.  We know a great deal about its electromotive and mechanical properties (torque, speed, changes in direction, and so forth) but we do not really know how it works.  We need more structural information.  This is hard, because essential components are membrane embedded.  But even in an age of systems biology, one should not be embarrassed to focus on an isolated network controlling a particular molecular machine. (Emphasis added in all quotes.)

1Q&A: Howard Berg, Current Biology, Volume 15, Issue 6, 29 March 2005, Pages R189-R190, doi:10.1016/j.cub.2005.03.003.

And yet he says, “Chemotaxis evolved so that cells can locate nutrients….”  Who would have imagined, indeed.  But then, when entering the high-performance world of microtechnology, imagination is what keeps the evolutionary story lubricated.  Alcohol helps, too (see 08/12/2004 entry); some evolutionists seem to have converged on that form of chemotaxis after watching Unlocking the Mystery of Life.

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