Component of bacterial flagela

A bacterial flagellum has 3 basic parts: a filament, a hook, and a basal body. 1) The filament is the rigid, helical structure that extends from the cell surface. It is composed of the protein flagellin arranged in helical chains so as to form a hollow core. During synthesis of the flagellar filament, flagellin molecules coming off of the ribosomes are transported through the hollow core of the filament where they attach to the growing tip of the filament causing it to lengthen. With the exception of a few bacteria, such as Bdellovibrio and Vibrio cholerae, the flagellar filament is not surrounded by a sheath. 2) The hook is a flexible coupling between the filament and the basal body . 3) The basal body consists of a rod and a series of rings that anchor the flagellum to the cell wall and the cytoplasmic membrane. Unlike eukaryotic flagella, the bacterial flagellum has no internal fibrils and does not flex. Instead, the basal body acts as a rotary molecular motor, enabling the flagellum to rotate and propel the bacterium through the surrounding fluid. In fact, the flagellar motor rotates very rapidly. (Some flagella can rotate up to 300 revolutions per second!) The MotA and MotB proteins form the stator (def) of the flagellar motor and function to generate torque for rotation of the flagellum. The MS and C rings function as the rotor (def). Energy for rotation comes from the proton motive force (def) provided by protons