When considering the assembly process involved in the bacterial flagellum, there exists a sequence that must be followed for successful assembly. There are three groups of genes labeled Class I, Class II, and Class III which must be assembled in order. The assembly process includes several key check points (feedback loops) that must be satisfied during the expression of each class of genes in the hierarchy, or the succeeding sets of genes are transcriptionally arrested. (Darwin’s Nemesis p. 214-15)
The flagellum is a true nanomachine of remarkable complexity in structure and assembly control. This macromolecular machine self-assembles and repairs, displays assembly control and processing, operates with two gears, is fueled by proton motive force, and the apparatus is "hard-wired" to a sensory apparatus that functions on short-term memory (chemotaxis). Rotor speeds for E. coli are estimated at 17,000 rpm but motors of some marine vibrios have been clocked upward of 100,000 rpm. (Darwin’s Nemesis p. 215)
The type III secretory system (TTSS) portion of the bacterial flagellum has a function elsewhere, however, the other thirty proteins in the flagellar motor, that are not present in the TTSS, are unique to the motor and are not found in any other living system. From whence were these protein parts co-opted? Even if all the protein parts were somehow available to make a flagellar motor during the evolution of life, the parts would need to be assembled in the correct temporal sequence similar to the way an automobile is assembled in a factory. Finally, the phylogenetic analyses of the gene sequences show that the flagella proteins arose first and those of the TSS came later. In other words, if anything, the TSS (less complex) evolved from the flagellum (more complex). (Darwin’s Nemesis p. 222)
(Excerpted from Darwin’s Nemesis, William Dembski, Editor)
Scott Minnich received his Ph.D. at Iowa State University, and conducted postdoctoral work at Princeton University and Purdue University.
Stephen C. Meyers has a Ph.D. from the University of Cambridge in the History and Philosophy of Science.
William A. Dembski has a Ph.D. in philosophy, a Ph.D. in mathematics and a M.S. in Statistics from the University of Chicago. He also has a M. Div. degree from Princeton Theological Seminary.
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