Lecture 16 Flashcards
Flagella that move CW move the bacteria in which direction?
tumble
Flagella that move CCW move the bacteria in which direction?
forward
What is chemotaxis?
Bacteria can move towards growth-promoting chemicals and away from toxic chemicals
directs the cell’s movement by controlling the frequency of runs and tumbles
What is biased random walk?
net movement towards chemical attractant
What is aerotaxis?
response to oxygen
Magnetotaxis is found in where?
swamps and ponds
Where is chemosensory array found?
end of cell (pole)
What is CheA?
histidine kinase
What is CheY?
response regulator
What does CheR do?
CheR methylates the MCP receptor giving it ”chemical memory”
What is accommodation?
The methylation of MCP makes it so that only a higher concentration of chemoattractant will trigger a run – only move to greener pastures
doesn’t occur with repellants
How does chemotaxis help bacteria? (4)
survival mechanism, growth promoting mechanism, virulence factor (helps colonize a host), persistence factor (biofilm)
What are the 4 methods of motility in bacteria?
gliding, twitching, swimming, and swarming
What is gliding?
the ability of certain rod-shaped bacteria to translocate on surfaces without the aid of external appendages such as flagella, cilia, or pili
move smoothly, move fast, snake like movement, surfaces
What is twitching?
Twitching motility is a flagella-independent form of bacterial translocation over moist surfaces using a type IV pili. —- grappling hook, slower, usually use multiple pili, surfaces
What is swimming?
bacterial movement by an individual cell powered by rotating flagella, fast moving, CW and CWW flagella movement
fastest method of movement, not as good for choosing directionality of movement, liquis
What is swarming?
Swarming= rapid multicellular bacterial surface movement powered by rotating flagella
OR
Swarming= a specific type of motion in which rod-shaped flagellated bacteria migrate rapidly on surfaces en masse
not group swimming, not a lot of bacteria does this, regulation from chemo-sensory mechanisms, surface but ideal is liquid
What is special about myxococcus xanthus?
has Gliding and twitching motility utilizing two engines, secretes slime for movement, can be dormant (myxospores - protective coats, outside bacteria purposely die to protect others)
