BISC300 Lecture Notes - Lecture 7: Cell Membrane, Firmicutes, Rings Of Saturn
24 Feb 2020
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Bacteria Flagellar Movement
● Flagellum rotates like a propeller
○ Up to 1100 revolutions/sec
○ Counterclockwise
■ Causes a forward motion
■ Disrupts run causing cell to stop and tumble (turing in a circle)
○ Chemotaxis
■ Going towards chemical reactions and away from harmful substances
● Chemoreceptors sense changing concentrations of chemical
attractants / repellent.
■ Without a chemical gradient
● Flagella cycle between counterclockwise (run) and clockwise
(tumeble) with no overall directional movement.
■ With a chemical gradient
● Runs longer
● Tumbles are shorter
● Leads to directional movement toward the higher concentration of
the attractant
■ Movement may be in response to temperature, light oxygen, osmotic
pressure, gravity, even magnetic fields.
○ Two part motor system
■ Rotor
● C ring (FliG protein) and MS ring turn and interact with stator
■ Startor
● Mot A and Mot B proteins
○ Form chemical channel through plasma membrane
○ Rotation driven by proton motive force across plasma
membrane
○ Protons move through Mot A and Mot B channels
○ Torgue powers rotation of the basal body and filament
○ Swarming-Coordinated movement of bacterial as population
■ Occurs on moist surfaces as a type of group behavior by bacteria
■ Driven by flagella
■ Most swarmers have peritrichous flagella
■ Production of molecules that aid movement is typical (slime later)
Bacterial endospore
○ Spores
■ Are complex, dormant structures formed by some gram (+) bacteria
(firmicutes, specifically)
■ Classified by location within the cell
■ Can survive adverse environmental conditions
Document Summary
Disrupts run causing cell to stop and tumble (turing in a circle) Going towards chemical reactions and away from harmful substances. Chemoreceptors sense changing concentrations of chemical attractants / repellent. Flagella cycle between counterclockwise (run) and clockwise (tumeble) with no overall directional movement. Leads to directional movement toward the higher concentration of the attractant. Movement may be in response to temperature, light oxygen, osmotic pressure, gravity, even magnetic fields. C ring (flig protein) and ms ring turn and interact with stator. Rotation driven by proton motive force across plasma membrane. Protons move through mot a and mot b channels. Torgue powers rotation of the basal body and filament. Occurs on moist surfaces as a type of group behavior by bacteria. Production of molecules that aid movement is typical (slime later) Are complex, dormant structures formed by some gram (+) bacteria (firmicutes, specifically) Spore surrounded by thin covering called exosporium. Thick layers of protein from the spore coat.
