Question

Which of the following description of chemotaxis is correct for polar forms A. Attractant starts counterclockwise rotation of flagellum = a run. B. Loss of stimulus reverses direction of flagellum bacterium tumbles. C. Attractant makes flagella sweep toward one end and rotate = a run D. Loss of stimulus and flagella loose coordination and bacterium tumbles.

Answer 1

Answer - A. Attractant starts counterclockwise rotation of flagellum= a run.

Chemotaxis is the movement of an living cell towards the chemical in the environment. In unicellular organisms like bacteria and amoebae it is used. Flagella are used by the host to recognize bacteria and they play role in motility. some bacteria have flagella and they can rotate in two ways-

1. Counter clockwise rotation - causing the bacterium to swim in a straight line.

2. Clockwise rotation- causing the bacterium to tumble in place.

The proteins Che W, Che Y and Che A play role in flagella regulation.They bind to the receptor, absence of receptor activation results in autophosphorylation in the histidine kinase. Che A is the histidine kinase. Responce regulator protein Che B takes phosphoryl group group from Che A. Bactria use signal transduction mecanism for flagellar regulation. Che Y protein induces tumbling of flagella bye interacting the flagellar switch protein FliM which induce a change from counter-clockwise to clockwise rotation of the flagellum. Change in the rotation state of a single flagellum can disrupt the entire flagella bundle and cause a tumble.