Random Walk and Chemotaxis of E. coli

Question 1

when does E. coli move in a random walk

Answer 1

if not in a gradient of attractant. walk composed of short run and then a tumble etc

Question 2

when does chemotaxis occur

Answer 2

in a gradient of attractant

Question 3

when does the length of a run increase. why

Answer 3

if cell is moving up a gradient of attractant. as more attractant is bound to the MCP, CheA autophosphorylation is inhibited

Question 4

when is the length of a run decreased. why

Answer 4

if cell movesdown the gradient of attractant. there will be fewer attractant bound to MCP. CheA will autophosphorylate and in turn will phosphrylate CheY and CheB

Question 5

How does the cell stay in an area with high [attractant]

Answer 5

CheR contd to methylate the MCP but now CheB is not being phosphorylated so level of methylation is high. this produces a conformation change in MCP that permits CheA to autophosphorylate and in turn phosphorylate CheY, cell will tumble

Question 6

How doe E. coli mutants w/non fn MCP take up sugar

Answer 6

they still have normal chemotaxis of sugars take up by group translocation

Question 7

e2b

Answer 7

e2b