prokaryotic vs eukaryotic chemotactic movement

Question 1

How do bacteria detect chemical gradients?

Answer 1

Temporal sensing via methyl-accepting chemotaxis proteins (MCPs).

Question 2

What is the role of MCPs in bacterial chemotaxis?

Answer 2

MCPs detect attractants or repellents and regulate the activity of the CheA histidine kinase.

Question 3

How is the chemotactic signal transduced in bacteria?

Answer 3

CheA phosphorylates CheY which controls flagellar motor rotation

Question 4

How do bacteria adapt to persistent stimuli?

Answer 4

By methylation and demethylation of MCPs, mediated by CheR (methyltransferase) and CheB (methylesterase).

Question 5

What determines bacterial movement during chemotaxis?

Answer 5

The phosphorylation state of CheY, which controls runs (counterclockwise flagellar rotation) and tumbles (clockwise rotation).

Question 6

How do amoeboid cells detect chemical gradients?

Answer 6

spatial sensing via GPCRs spaced across cell membrane

Question 7

What is the main signaling pathway in amoeboid chemotaxis?

Answer 7

GPCR activation triggers pathways involving G-proteins like IP3 Rac and Rho

Question 8

What drives amoeboid cell movement?

Answer 8

actin polymerisation at leading edge to extend pseudopodia, and myosin-II contraction to retract the rear.

Question 9

How do amoeboid cells adapt to sustained stimuli?

Answer 9

By receptor desensitization and phosphatase activity to modulate signaling.

Question 10

What is the function of PIP3 in amoeboid chemotaxis?

Answer 10

localises leading edge amplifying polarity and directing movement

Question 11

What is a common feature of chemotaxis in bacteria and amoeboid cells?

Answer 11

both rely on receptor-mediated detection of chemical gradients and intracellular signaling pathways.

Question 12

How do both systems ensure continued responsiveness to gradients?

Answer 12

feedback mechanisms

Question 13

What is the ultimate goal of chemotaxis in both systems?

Answer 13

to move towards higher concentrations of attractants or away from repellents

Question 14

How do bacteria sense gradients differently from amoeboid cells?

Answer 14

bacteria use temporal sensing
amoeboid use spacial sensing

Question 15

What is the difference in movement mechanisms between bacteria and amoeboid cells?

Answer 15

bacteria move via flaggelar rotation
amoeboid move via actin based crawling

Question 16

What signaling pathways are unique to each system?

Answer 16

bacteria use Che protein 2 component system
amoeboid use GPCR mediated signalling

Question 17

How does systems biology help in understanding bacterial chemotaxis?

Answer 17

Through modeling of CheY phosphorylation dynamics and run-tumble behavior.

Question 18

What role does network analysis play in studying chemotaxis?

Answer 18

identifies signalling components and feedback systems