E. coli Motility: Understanding Bacterial Movement with Flagella

*E. coli* move around by means of flagella. Flagella are long, whip-like structures that are made up of the protein flagellin. Flagellin is synthesized by the *flhDC* operon, which is regulated by the master regulator FlhD4C2 (formerly known as FlhDC).

The flagellum is composed of a basal body, a hook, and a filament. The basal body is embedded in the cell membrane and contains the motor that drives the flagellum. The hook is a short, curved structure that connects the basal body to the filament. The filament is a long, thin structure that is responsible for the movement of the cell.

*E. coli* can move in either a clockwise or counterclockwise direction. When the flagella rotate clockwise, the cell moves in a straight line. When the flagella rotate counterclockwise, the cell tumbles. This tumbling motion allows the cell to change its direction of movement.