Movement of Bacteria

Question 1

motility

Answer 1

the ability to propel your own movement

Question 1

are all bacteria motile

Answer 1

no, for example yersinia pestis
-loss of y.pestis motility may contribute to virulence?

Question 2

flagellum

Answer 2

-the flagellum complex multi-protein machine that powers bacterial movement
-around 50 proteins involved in flagellum
-includes a long, thin, filament that acts like propeller
-rotated using a motor that is anchored in the cell envelope
–swim through fluids
-can also be used for swarming (solid surface)

Question 3

different arrangments of flagella

Answer 3

-petrichous (many across pole and body)
-monotrichous (single at the pole)
-lophotrichous (many all at the pole)
-amphitricous (both poles)
-atrichous (no flagella)

Question 4

petrichous flagella movement

Answer 4

-longer runs - counterclockwise - cell moves forward
-short tumbles - clockwise - tumbles and assumes new position

Question 5

what dictates direction of movement

Answer 5

-motor switching from CCW to CW

Question 6

monotrichous flagella movement

Answer 6

-reversible flagellum - rotation in opposite direction reverses firection of movement
-unidirectional flagella - rotation stops and starts, random movement during stops changes direction of bacterium

Question 7

3 segments of flagellum

Answer 7

-filament - long thin propeller
-hook - adaptor that connects filament to basal body
-basal body - core of the structure and powers rotation of filaments

Question 8

flagellar motor

Answer 8

-proton motor force
->20 proteins anchored in cytoplasmic membrane and cell wall
-central rod passes through MS ring, C ring P ring and L ring
-stator couples flow of protons to rotation of MS ring (proton turbine)
-MS ring rotates rod and ultimately hook and filament
-L/P rings act like bearings to help rotation

Question 9

what is the C ring important for

Answer 9

-generating torque, switching motor direction, and flagellin secretion

Question 10

what do gram positive flagellum lack

Answer 10

P/L rings, they only have C/MS rings

Question 11

flagellar filament

Answer 11

-long filament that drives movment is mafe of thousands of copies of a single protein called flagellin
-very long and narrow
-rigid helical and hollow
-conserved in bacterial flagella but its sequence varies
-detected by our immune system and is an important antigen
-often used in serotyping (h antigen)

Question 12

synthesis of the flagellum by bacteria

Answer 12

-the overall structure is built from the inside out
-innermost stuff assembles first
-flagellin grows from outside
-produces in cytoplasm and is secrteed through flagellum via hollow filament
-new subunit assembles at end with help of cap proteins

Question 13

type III secretion system

Answer 13

-used to export flagellin
-a related system is used as a protein toxin injection system by certian pathogens

Question 14

variations of flagellar motility

Answer 14

-some bacteria have motors that use the Na gradietn instead of PMF
-spirochetes have a flagellum that resides in periplasm resulting in corkscrew motion of entire bacterium
-flagellzf motility highly regulated even motile bacteria can adopt atrichous non-motile state

Question 15

taxis

Answer 15

-directed movement of bacteria
-accomplished using a bias random walk

Question 16

chemotaxis

Answer 16

-movement in the direction of gradient of incrrsdomh or decreasing concentration
-chemoreceptors detect specific chemicals
-pass info on to proteins that control direction of the motor
-if moving toward desirable nutrient tumbles are inhibited, longer runs less frequent tumbles
-if moving away shorter runs more frequent tumbles

Question 17

phototaxis

Answer 17

-moveement toward/away fro, light
-detectors for light

Question 18

aerotaxis

Answer 18

-directed motility in response to O2

Question 19

twitching motility

Answer 19

-some bacteria can move using other typees of motility
-type IV pilus attaches to a surface and then retracts
-like a grappling hook