Midterm 1.4

Question 1

Explain substrate binding proteins (periplasmic binding proteins) in gram + and gram - bacteria

Answer 1

Prokaryotic transporters are best studied in gram - bacteria which use those proteins to capture their ligand within the periplasm
In archaea and gram + bacteria the substrate binding protein is tethered to the cytoplasmic membrane

Question 2

Motility

Answer 2

The ability to propel your own movement

Question 3

Flagellum (!)

Answer 3

A large, complex, multi-protein machine that powers bacteria movement
Includes a long, thin filament that acts like a propeller. Rotated using a motor that is anchored in the cell envelope (!)

Question 4

Swarming

Answer 4

Coordinated multicellular movement across a solid surface

Question 5

Petrichous

Answer 5

Many flagella across pole/body

Question 6

Lophotrichous

Answer 6

Many flagella, all at one pole

Question 7

Amphitrichous

Answer 7

Flagella at both poles

Question 8

Atrichous

Answer 8

No flagella at all

Question 9

What are the 3 segments of the flagellum? Briefly describe each

Answer 9

1. Filament (long, thin propeller - drives movement)
2. Hook (adaptor that connects filament to the basal body)
3. Basal body (core of the structure. Powers rotation of filaments)

Question 10

What is the function of the flagellar motor?

Answer 10

Harnesses proton motive force to drive rotation

Question 11

What is the flagellar motor composed of in gram - bacteria?

Answer 11

Central rod passes through a series of rings: C-ring (cytoplasm), MS-ring (cytoplasmic membrane), P-ring (peptidoglycan) and L-ring (outer membrane) gram -

Question 12

What is the function of stator?

Answer 12

Couples flow of protons to rotation of the MS ring - behaves like a “proton turbine”

Question 13

What is the function of MS ring?

Answer 13

Rotates rod and hook and filament

Question 14

What is the function of L/P rings?

Answer 14

Act like bearings (or bushings) to help rotation

Question 15

What is the function of C ring?

Answer 15

Generating torque, switching motor direction, flagellin secretion

Question 16

What is the difference in the flagellar motor between gram - bacteria and gram + bacteria?

Answer 16

Gram + lacks P/L rings (only has C/MS rings)

Question 17

Flagellin

Answer 17

Thousands of copies of a single protein - part of the long filament that drives movement

Question 18

What are the 3 properties of flagellin?

Answer 18

Rigid, helical and hollow

Question 19

How is flagellum synthesized?

Answer 19

Made from inside out
Produced in cytoplasm & secreted via the “export apparatus”
“Type III secretion system” used to export flagellin: a related system is used as a protein toxin injection system by certain bacterial pathogens

Question 20

Twitching motility

Answer 20

A type IV pilus attaches to a surface and then retracts (sort of like a grappling hook)

Question 21

Inclusions - define it and describe the function

Answer 21

Bodies or aggregates within the cell
- Can have diverse functions - often related to storage of a substance

Question 22

Microcompartments

Answer 22

Protein shells that encase specific enzymes/metabolites/cofactors that carry out specific metabolism

Question 23

What is the most common carbon storage polymer? (!)

Answer 23

Poly-beta-hydroxybutyric acid (PHB)

Question 24

When is carbon storage polymer produced?

Answer 24

When there is an excess of carbon/energy - aggregates and forms large granules
Granules/polymerase broken down for carbon/energy when needed

Question 25

Polyphosphate granules

Answer 25

Excess of phosphate - broken down to produce nucleic acids/phospholipids

Question 26

Sulfur storage granules

Answer 26

Produced by bacteria and archaea that oxidize reduced sulfur compounds for energy/CO2 fixation