1. Basal Body:
* Rod: This is a central rod that extends through the cell wall and inner membrane.
* Rings: The rod is surrounded by rings that anchor the flagellum to the cell wall. In Gram-negative bacteria, there are four rings:
* L Ring: Located in the outer membrane.
* P Ring: Located in the peptidoglycan layer.
* S Ring: Located in the periplasmic space.
* M Ring: Located in the inner membrane.
* In Gram-positive bacteria, only the M and S rings are present.
* Rotor: This is a protein complex within the basal body that rotates the flagellum.
2. Hook:
* This is a short, curved structure that connects the basal body to the filament. It acts as a flexible joint, allowing the flagellum to bend and change direction.
3. Filament:
* This is the long, helical structure that extends from the hook and propels the bacterium.
* The filament is composed of thousands of protein subunits called flagellin, which assemble into a hollow, helical structure.
Other components:
* Mot proteins: These proteins are located in the basal body and are responsible for generating the torque that rotates the flagellum.
* Fli proteins: These proteins are located in the basal body and control the direction of rotation of the flagellum.
In summary, the bacterial flagellum is a complex structure composed of multiple protein components that work together to allow the bacterium to move.
