Episode Details

A scientist who specifically studies the bacterial flagellum using some of the most cutting-edge research tools clears up a few myths and misconceptions.

Much of Dr. Michael Behe’s defense of Intelligent Design rests on claims made about the bacterial flagellum. It certainly has become his signature, and one could even say it’s become the symbol or mascot of the ID movement (like the polar bear became for the global warming movement). Some of his claims are often challenged by opponents of ID. To shed some light on the subject, we reached out to several scientists who actually work with the bacterial flagellum (Behe does not). Here, we speak to Dr. Nicholas Mitzke, who gives us a basic introduction to this bacterial machine, demystifying it and clearing up some misconceptions that have been built up around it. Points that we discussed included:

• misconception #1: the flagellum is not just one unique thing that cannot be altered in any way without completely losing its function. There are in fact thousands of different versions of the flagellum, each with differences in their amino acid sequence (which necessarily means their gene sequence was changed), and some of them are even missing certain protein parts, and yet all of these altered versions retain their function.
• misconception #2: the flagellum did not in fact arise through a series of intermediate steps, each intermediate being non-functional, before finally becoming a functional machine. Instead, we’re now getting glimpses of its evolutionary journey through various stages of different functionality.
• proteins in general can evolve, changing amino acid sequences in many ways, and yet retain their original shape, and therefore full function
• how the rotary engine in the flagellum converts chemical energy into a rotational movement; it uses an acid battery that spins an “electric” rotor
• the flagellum is made of multiple copies of 20 proteins; 99% of the flagellum is the long whip (tens of thousands of copies of one particular protein); the other 19 proteins are at the base of the flagellum, forming one machine that