FIGURE 1.

(A) Schematic representation indicating relative orientation of three components of the bacterial flagellum: basal body, responsible for torque generation; filament, essentially a long rigid rod; and hook, a flexible linking region. The figure is not drawn to scale; hence, representative lengths of filament and hook are noted. Dotted lines interrupting the filament represent a long section removed for figure clarity. (B and C) Cartoon portrayals of a flagellated bacteria, depicting how bending at the hook may allow bundling of adjacent filaments, leading to in-phase rotation.