The end of bacterial flagella that is near the cell is a marvel of mechanical miniaturization — a molecular wheel that turns, just like the axle of a car. The assembly consists of a stator, the part that holds it in place, and a rotor, the part that turns. The rotor is a beautifully complex structure consisting of a basal body and a hook to which the flagellar filament is attached. Several dozen proteins are involved. And it self-assembles!
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