Microbiology: Chapter 2 continued

Question 1

What does the M-ring do in a Gram positive flagellum?

Answer 1

Turns the entire structure. (Ex: if feet were M-ring, arm was filament and shoulder was the hook, entire structure rotates)

Question 2

Why are the P-ring and S-ring important in a Gram positive flagellum?

Answer 2

They prevent the flagellum structure from ripping apart if the cell gets stuck on something. This protects the cell membrane and keeps the cell alive.

Question 3

What is the function of the S-ring in a Gram positive flagellum?

Answer 3

Provides structural support.

Question 4

What role does the curved part of the hook play in a Gram positive flagellum?

Answer 4

It makes the filament extend away from the cell so the flagellum can rotate freely, propelling the bacterium without hitting the cell surface and generating torque.

Question 5

What is the filament of a flagellum made of?

Answer 5

Flagellin subunits, which are small, repeating protein-based units.

Question 6

How are flagellin subunits synthesized and assembled?

Answer 6

Protein subunits are synthesized at the ribosome and transported up the rod to build the filament.

Question 7

What is the purpose of cap proteins at the end of the filament?

Answer 7

They prevent things from entering the cell at the tip of the filament.

Question 8

What happens if there isn’t enough proton supply for the flagellar motor?

Answer 8

The filament may break off or may not be produced at all, resulting in no functional flagellum.

Question 9

How long does it take to build a filament?

Answer 9

About 20 minutes.

Question 10

What two conditions must be met to build a filament?

Answer 10

1. The environment must be suitable (liquid environment).
2. The cell must have the energy to build it.

Question 11

How much ATP is needed to add one amino acid to a peptide?

Answer 11

4 ATP per amino acid (ex: a 100 amino acid filament requires 400 ATP).

Question 12

What is the consequence of a filament breaking off?

Answer 12

All the energy used to build the cell and filament is lost, and the process must start from scratch.

Question 13

What parts are replicated instead of reconstructed during binary fission or if a filament is killed?

Answer 13

motA and motB, M-ring, S-ring, P-ring, hook, and rod.

Question 14

How does a Gram negative flagellum differ from a Gram positive one?

Answer 14

It has all the same parts plus an L-ring located in the lipopolysaccharide layer. P-ring is in the peptidoglycan layer. L-ring, S-ring, and P-ring stabilize the structure.

Question 15

Where are protons located in Gram negative flagella?

Answer 15

Only in the periplasmic space.

Question 16

How much ATP/proton is required to flip the Gram negative flagellar structure?

Answer 16

3 ATP / 3 protons. Still expensive to run.

Question 17

What are nonmotile bacteria?

Answer 17

Bacteria with no ability to produce flagella (cannot make m-ring, s-ring, p-ring, L-ring, hook, rod, or filament).

Question 18

What are atrichous bacteria?

Answer 18

Genetically capable of producing flagella but currently not using or building a filament. Without the filament, they cannot move, even if other parts are present. Phenotypically nonmotile.

Question 19

Define monotrichous flagella.

Answer 19

Single polar flagellum. (Mono = 1)

Question 20

Define amphitrichous flagella.

Answer 20

Single flagellum (or a tuft) at both ends (poles) of the cell. (Amphi = at both ends)

Question 21

Define lophotrichous flagella.

Answer 21

A tuft of flagella at one pole of the cell. (Lopho = tuft/cluster in one spot)

Question 22

Define peritrichous flagella.

Answer 22

Multiple flagella dispersed over the surface of the cell. (Peri = all around)

Question 23

How do multiple flagella work together?

Answer 23

They rotate together and use energy, but coordination is not always perfect. Cells move in tumbles and runs.

Question 24

What does it mean when filaments form bundles?

Answer 24

Bundles help propel the cell, but if disorganized, the bundle can collapse and the cell must start moving again.

Question 25

What are tumbles and runs?

Answer 25

Tumbles: filament bundle flips over itself. Runs: forward movement when bundle is organized.

Question 26

What is archaeaillum?

Answer 26

Archaea don’t produce flagella; they produce archaeaillum.

Question 27

Describe axial filaments.

Answer 27

Very long, thin structures that move in a cork-screw motion. Structurally similar to flagella but embedded in the cell membrane.

Question 28

How do axial filaments move the cell?

Answer 28

They twist/contract to move the cell in a spiral shape. Relaxation stops movement.

Question 29

How are axial filaments structurally related to Gram negative flagella?

Answer 29

They have M-ring, S-ring, P-ring, L-ring but no filament extending off them.