Sulfate reduction

Question 1

What is the terminal electron acceptor in sulfate reduction?

Answer 1

Sulfate

Question 2

What is the end product in sulfate reduction?

Answer 2

Hydrogen sulfide

Question 3

How good is sulfate reduction for energy production?

Answer 3

Not very good. Its still better than fermentation, but way worse than aerobic respiration

Question 4

What sort of bacteria have sulfate reduction?

Answer 4

Ones that live in unique environments where better pathways don’t work

Question 5

What is the first step of sulfate reduction?

Answer 5

Activation of sulfate by adding an ATP to it to form APS

Question 6

Why does sulfate need to be activated before it can be used for metabolism?

Answer 6

Too stable

Question 7

Which enzyme catalyzes the first step of sulfate reduction?

Answer 7

ATP sulfurylase

Question 8

What is the second step of sulfate reduction?

Answer 8

The sulfate reduction. APS is reduced to sulfite by adding 2 electrons and releasing an AMP

Question 9

Which enzyme catalyzes the reduction of APS to sulfite?

Answer 9

APS reductase

Question 10

What is the third step of sulfate reduction?

Answer 10

A series of sulfite reductions catalyzed by sulfite reductase

Question 11

How many electrons get added to sulfate for it to become fully reduced into H2S?

Answer 11

8

Question 12

What enzyme catalyzes the series of sulfite reductions?

Answer 12

Sulfite reductase

Question 13

What is the source of electrons in sulfate reduction? How is this different from other metabolic pathways?

Answer 13

Comes from H2 gas or lactate. They come from NADH made in glycolysis and the CAC for the other systems

Question 14

How are electrons derived from H2 gas for sulfate reduction?

Answer 14

Hydrogenase in the periplasm transfers electrons from H2 to the ETC and releases the protons into the periplasm to form the PMF

Question 15

How are electrons derived from lactate for sulfate reduction?

Answer 15

Lactate is oxidized to pyruvate by lactate dehydrogenase in the cytoplasm. The pyruvate gets converted to acetate, 1 ATP, CO2 and a bit of H2 gas that goes to hydrogenase

Question 16

How many ATP does the cell get for using H2 gas as its electron source?

Answer 16

1

Question 17

How many ATP does the cell get for using H2 gas as its electron source?

Answer 17

2

Question 18

Where is sulfate commonly found?

Answer 18

Marine sediments and ground water

Question 19

How does anaerobic corrosion of metal pipes containing iron occur?

Answer 19

H3O+ in the water reacts with Fe2+ in the pipe, which creates small H2 bubbles on the pipe’s surface. The bacteria can use the H2 bubbles and the sulfate in the water to create H2S, which reacts with the iron to form FeS as a precipitate