Flagella

Question 1

What drives a flagella?

and How many times can it rotate per second?

Answer 1

Flagella are driven by a rotary motor that is energized by an electrochemical ion gradient across the cell membrane.

Flagella can rotate more than 200 X/sec

Question 2

How many operons and classes are flagella put into?

Answer 2

The genetic system governing the synthesis and function of flagella in E. coli is composed of 14 operons arranged in a regular cascade of three classes.

Question 3

Class 1 vs 2 vs 3

Answer 3

Class 1 operon: encodes transcriptional activator of class 2 operons.

Class 2 genes include the structural components of the rotary motor and hook structures, and transcriptional activator for class 3 operons.

Class 3 genes include flagellar structural genes and the chemotaxis signal transduction system that directs cellular motion.

A mechanism exists that ensures that class 3 genes are not transcribed before structural assembly is complete.

Question 4

Two Mot Proteins:

associated with?

enable what?

and what does each specifically do?

Answer 4

Mot proteins A and B

Associated with cell membrane and surround the MS-ring
Components of torque generators that enable motor rotation
Mot A is involved in conducting protons across the CM
Mot B links Mot A and other torque-generating machinery to the cell wall (stabilizes/stationary with respect to the rest of the cell)

Question 5

What constitutes the flagellar motor?

what affect changing in rotation?

Answer 5

Mot A and Mot B plus the flagellar switch proteins (FliG, FliM, and FliN) constitute the flagellar motor

FliG, FliM, FliN proteins affect rotation and are involved in changing rotations from CW to CCW.

Question 6

S-layer?

Answer 6

Surface layer
Role or function considered unknown
Protection
Collection of nutrients
Likely serves as a cell wall for Archea