Diameter of flagella

Value 20 nm
Organism Bacteria Escherichia coli
Reference Neidhardt et al Physiology of the Bacterial Cell, second edition 1996 chapter 10- Flagella and motility
Primary Source Namba K, Yamashita I, Vonderviszt F. Structure of the core and central channel of bacterial flagella. Nature. 1989 Dec 7 342(6250):648-54.PubMed ID2687696
Method X-ray fibre diffraction analysis
Comments The filament is of variable length (typically 5 to 10 mm) but has a constant diameter of about 20 nm throughout its length (Primary source).The bacterial flagellum differs from the eukaryotic flagellum in several regards: (i) the bacterial flagellar filament, ca. 20 nm in diameter, consists of subunits of just one protein, whereas the eukaryotic flagellum has a complex architecture and is much thicker, ca. 200 nm in diameter (ii) the filament does no chemomechanical work but is passively driven by a motor at its base (iii) the mechanism is one of rotation (8, 173), not bending (and hence the term 'flagellum,' meaning 'whip,' is misleading) (iv) the motor can operate in either the counterclockwise (CCW) or clockwise (CW) direction (173) (i.e., it possesses a switch) and (v) the energy source is the transmembrane proton potential (proton motive force) (139), not ATP (121). (Numbers in parentheses refer to literature cited in Reference).
Entered by Ron Milo, Paul Jorgensen, Mike Springer
ID 100096