Write a note on Flagella,Pili,and Fimbriae.

(N/A) $\Rightarrow$ Flagella: Bacterial cells may be motile or non-motile. If motile,they possess thin filamentous extensions from their cell wall called flagella. Bacteria show a range in the number and arrangement of flagella. $A$ bacterial flagellum is composed of three parts: filament,hook,and basal body. The filament is the longest portion and extends from the cell surface to the outside.
$\Rightarrow$ Pili: Pili are elongated,tubular structures made of a special protein. They are surface structures but do not play a role in motility.
$\Rightarrow$ Fimbriae: Fimbriae are small,bristle-like fibers sprouting out of the cell. In some bacteria,they are known to help attach the bacteria to rocks in streams and also to host tissues.