The flagellum

The most general means of locomotion in prokaryotes is through the rotation of flagella. These act as propellers allowing the cell to swim by liquid media. The single cell may have several flagella spread all over the surface of the cell, the flagella may be polar found at one or both ends amphitrichous if only two in total. Lipotrichous flagella grow in tufts from one position on the cell surface. Every flagellum is not straight but is helix shaped with the length, wavelength and amplitude of the helix varying from species to species. While the presence or absence the properties and the position of the flagella can be used as taxonomic characters all bacterial flagella are composed of the similar protein which is flagellin. However, much like cell wall composition the situation in Archaea is very different in which there are many different proteins in this kingdom which perform analogous functions.