What is the chemical composition of the shaft of a bacterial flagellum?

Answer 1

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 thought to be 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 (see Fig. 1).

2) The hook is a flexible coupling between the filament and the basal body (see Fig. 1).

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 (see Fig. 1). Unlike eukaryotic flagella, the bacterial flagellum has no internal fibrils and does not flex. Instead, the basal body acts as a molecular motor, enabling the flagellum to rotate and propell the bacterium through the surrounding fluid. In fact, the flagellar motor rotates very rapidly. (The motor of E. coli rotates 270 revolutions per second!)

Answer 2

flagellin protien (antigenic determinant)