Chapter 2.9-2.11

Flagella definition

threadlike appendages extending from the plasma membrane and cell wall

flagella functions

motility, movement to stimuli (taxis), attachment, and virulence factors

filament structure

long, helical structure made of flagellin protein

hook structure

connects filament to basal body; flexible coupling

basal body structure

anchors flagellum to cell wall/membrane, provides energy for rotation (motor)

energy for rotation comes from

proton motor force

proton motor force

movement of protons across membrane powers rotation

rotor function

spin/rotation

stator function

stays still and powers the spinning

MS ring

embedded in the cytoplasmic membrane, main spinning platform

C ring

attached to the inside of the MS ring, controls direction of rotation

MotA and MotB

form proton channel that allows H+ ions to flow through, this converts proton movement into mechanical energy

bacterial flagellar movement

rotates like a propeller, up to 1100 revolutions per second

counter clockwise rotation

forward motion, RUN

clockwise rotation

disrupts the run, TUMBLE, changes direction

alternating pattern

run and tumble

spirochete

multiple flagella form axial filaments (endoflagella)

endoflagella

periplasmic flagella found in spirochetes that wrap around the cell and generate corkscrew motion by rotating within the outer sheath

2 kinds of surface motion

twitching and gliding motility

chemotaxis

movement toward a chemical attractant or away from a chemical repellent

toward an attractant movement

runs are longer and tumbles are less frequent

toward a repellant movement

runs are shorter and tumbles are more frequent

what controls the run and tumble behavior

chemotaxis

monotrichous

one flagellum

polar flagellum

flagellum at one end of the cell

amphitrichous

one flagellum at each end

lophotrichous

tuft of flagella at one or both ends

peritichous

flagella spread over entire surface of cell