Flagellum

A flagellum is a tail-like projection that protrudes from the cell body of certain prokaryotic and eukaryotic cells, and functions in locomotion [1]. Three types of flagella are found– bacterial, archaeal and eukaryotic flagella. Bacterial flagella are helical filaments that rotate like screws (Fig. 1) [1]. Eukaryotic flagella are complex cellular projections that lash back and forth [1].

Fig. 1: Flagellum of Gram-negative Bacteria[1]

Fig. 2: Euglena: a eukaryote with a flagellum [2]

References

[1] http://en.wikipedia.org/wiki/Flagellum

[2] http://www.daviddarling.info/encyclopedia/F/flagellum.html