Editing Evolution of flagella (section)

===Eubacterial flagellum ===
Eubacterial flagellum is a multifunctional organelle. It is also one of a range of motility systems in bacteria. The structure of the organelle appears like a motor, shaft and a propeller.<ref name="Young&Taner2004">Young, Matt & [[Taner Edis|Edis, Taner]] (2004). ''Why Intelligent Design Fails: A Scientific Critique of the New Creationism'' {{ISBN|0-8135-3433-X}} Rutgers University press New Brunswick, New Jersey, and London.72-84.</ref> However, the structure of eubacterial flagellae varies based on whether their motor systems run on protons or sodium, and on the complexity of the flagellar whip.<ref>Berry, R. M., and J. P. Armitage. 1999. "The Bacterial Flagella Motor." Advances in Microbial Physiology {{ISBN|978-0-12-027749-0}}. v. 49: 291–337.</ref> The evolutionary origin of eubacterial flagellae is probably an example of indirect evolution. A hypothesis on the evolutionary pathway of the eubacterial flagellum argues that a secretory system evolved first, based around the SMC rod- and pore-forming complex. This is presumed to be the common ancestor of the type-III secretory system and the flagellar system. Then, an ion pump was introduced to this structure which improved secretion. The ion pump later became the motor protein. This was followed by the emergence of the proto-flagellar filament as part of the protein-secretion structure. Gliding-twitching motility arose at this stage or later and was then refined into swimming motility.<ref name="Young&Taner2004"/>