Flagella and Pili (Fimbriae)


Flagella are long, thin structures that protrude from the surface of some bacteria and allow them to move in liquid environments. They are composed of protein subunits called flagellin, which form a helical filament that rotates like a propeller. Flagella are one of the most distinctive and fascinating features of bacterial cells, as they enable them to sense and respond to their surroundings, colonize new habitats, and evade host defenses.