MMG 301 Study Guide - Final Guide: Bacterial Gliding, Phototaxis, Cell Envelope
17 Jul 2019
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Document Summary
Some helical bacteria exhibit swimming motility due to the presence of. These are flagella-like structures within the cell, located just beneath the outer cell envelope. Their mechanism of action is to cause the cell to twist and wriggle in order to produce movement. Some bacteria are motile only when in contact with a solid surface, they glide using flexing sinuous motion, this is a slow mechanism of motility, no specialized structures or organelles are associated with this ability. Positive - towards ; negative - away from the chemical itself is not the stimulus; the gradient in the chemical is the stimulus and is sensed via chemoreceptors located on the plasma membrane; receptors are specific for various attractants/repellants. Phototaxis is also possible (response it to light) in some species. The capsule is a viscous layer of complex polysaccharides and small proteins surrounding the cell, its precise chemical composition is unique to the species secreting it.
