Microbial Metabolism (Catabolism) Flashcards

1
Q

What is substrate-level phosphorylation?

A
  • used in fermentation and other pathways
  • ATP is synthesized during steps in the catabolism of an organic compound (glycolysis)
  • transferring a phosphate from an energy rich compound to ADP to make ATP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is oxidative phosphorylation?

A
  • used in respiration

- ATP is produced by proton motive force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is fermentation?

A
  • takes place in the absence of an exogenous electron acceptor (don’t need oxygen)
  • uses pyruvate or a pyruvate derivative as the electron acceptor
  • continues recycling of electron carriers (NADH from glycolysis oxidized to NAD+)
  • forms ATP via substrate level phosphorylation
  • produces various fermentation products (waste products)
  • does not use an ETC or proton motive force
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the different kinds of fermentation products?

A
  • ethanol: used to make breads, wine, and beer
  • lactic acid (homolactic): lactic acid is the only fermentation product; used to make certain cheeses, sour cream, and yogurt
  • lactic acid (heterolactic): makes lactic acid and other products; used to make sauerkraut, pickles, buttermilk; involved in food spoilage
  • mixed acid: tested for by MR test
  • 2,3-butanediol: tested for by the VP test, detects the intermediate acetoin
  • propionic acid: used to make swiss cheese
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is aerobic respiration?

A
  • respiration in which the final electron acceptor is oxygen
  • ATP is made primarily by oxidative phosphorylation where electron transport is used to generate proton motive force
  • ATPase involved
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is anaerobic respiration?

A
  • respiration in which the final electron acceptor is a different exogeneous acceptor such as NO3-, SO4-, CO2, Fe3+, or SeO42-
  • organic acceptors such as fumarate may also be used
  • still uses oxidative phosphorylation and an electron transport chain
  • yields less energy than aerobic respiration
  • E0’ of final electron acceptor is less positive than the E0’ of oxygen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the purpose of the MRVP test?

A
  • the MR test detects the production of mixed acids as a product of fermentation
  • the MR test uses methyl red as an indicator which turns red if the pH is below 5 (positive test)
  • the VP test detects the production of butanediol as a product of fermentation by testing for the precursor acetoin
  • the VP test uses Barritt’s A and Barrit’s B which will turn the solution red if acetoin is present, pH does not go below 5
  • should only test positive for one or the other
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where is the electron transport chain located in eukaryotes?

A

the inner mitochondrial membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where is the electron transport chain located in bacteria and archaeons?

A

the cytoplasmic membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the electron transport chain?

A
  • a series of electron carriers that operate together
  • transfers electrons from NADH and FADH2 to a terminal electron acceptor
  • electrons flow from carriers with a more negative E’0 to carriers with a more positive E’0
  • as electrons are transferred, energy is released to make ATP via oxidative phosphorylation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the P/0 ratio for NADH?

A

3 ATP per NADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the P/0 ratio for FADH2?

A

2 ATP per FADH2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does ATP synthase work?

A
  • protons are moved from the mitochondrial matrix to the intermembrane space by the complexes of the electron transport chain
  • the movement of protons establishes proton motive force
  • ATP synthase uses the proton flow down the concentration gradient to make ATP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the structure of ATPase?

A
  • C12: spinning C cylinders
  • a: channel for H+ ions to enter
  • b2: holds headpiece stationary
  • beta: brings ADP and Pi together and releases ATP
  • F1: headpiece
  • Fo: motor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the functions of proton motive force?

A
  • can be used to generate ATP
  • can be used to rotate the flagella (explains why fermentative bacteria have ATPase because it can work backwards to generate PMF)
  • PMF can sometimes be used instead of ATP to fuel active transport
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is aerobic catabolism?

A
  • aka aerobic respiration
  • completely catabolizing an organic energy source to CO2 using glycolysis, the Krebs cycle, and ETC with O2 as the final electron acceptor
  • produces ATP and recycles electron carriers
  • uses inducible exoenzymes (digestive enzymes) that can break down food in the environment
  • also uses constitutive endoenzymes to break down food
  • includes amphibolic pathways (both catabolic and anabolic enzymes)
17
Q

How many ATP and NADH are produced in glycolysis?

A
  • 2 ATP (substrate level)
  • 2 NADH x (3 ATP/NADH)= 6 ATP (oxidative phosphorylation)

total of 8 ATP

18
Q

How many ATP and NADH are produced in the bridge step?

A

2 NADH x 3ATP/NADH= 6 ATP (oxidative phosphorylation)

19
Q

How many ATP, NADH, and FADH2 are produced in the Kreb’s cycle?

A
  • 2 ATP (substrate level)
  • 6 NADH x 3 ATP/NADH= 18 ATP (oxidative phosphorylation)
  • 2 FADH2 x 2 ATP/FADH2= 4 ATP (oxidative phosphorylation)
20
Q

What is the maximum ATP yield of respiration?

A

38 ATP (34 from oxidative phosphorylation and 4 from substrate level phosphorylation)