An appendage used for movement or other functions. Bacterial flagella are driven by a bacterial flagellar motor; their construction differs from eukaryotic motile cilia.
A bacterial filament rotates as part of a motor-driven propeller, whereas a typical eukaryotic flagellum bends through microtubule-associated motor activity. The shared functional name therefore does not imply identical architecture or a single evolutionary origin for every appendage called a flagellum. [ref]
Molecular Biology of the Cell, 4th edition by Bruce Alberts and others. Chapter 16, Cilia and Flagella
New to topics? Read the docs here!