Chapter 7.8: Oxidation Without O2

Question 1

How does lactic acid fermentation work?

Answer 1

• This reaction converts pyruvate into lactic acid and regenerates NAD⁺ from NADH

Question 2

What does sulfur bacteria use as the electron acceptor?

Answer 2

• In sulfate respiration, the prokaryotes derive energy from the reduction of SO₄ to hydrogen sulfide (H₂S)

Question 3

What is the first step of ethanol fermentation?

Answer 3

• Yeast enzymes remove a terminal CO₂ group from pyruvate through decarboxylation, producing a 2-carbon molecule called acetaldehyde

Question 4

After Yeast enzymes remove a terminal CO₂ group from pyruvate through decarboxylation, producing a 2-carbon molecule called acetaldehyde what is the last step of ethanol fermentation?

Answer 4

• The acetaldehyde accepts a pair of electrons from NADH producing NAD⁺ and ethanol (ethyl alcohol)

Question 5

What is fermentation?

Answer 5

• In the absence of oxygen, cells that cannot utilize an alternative electron acceptor for respiration must rely exclusively on glycolysis to produce ATP
  
  • Under these conditions, the electrons generated by glycolysis are donated to organic molecules in a process called fermentation
    
    • Recycles NAD⁺

Question 6

What do methanogens use as an the elctorn acceptor?

Answer 6

Methanogens CO₂ as the electron acceptor, reducing CO₂ to CH₄

Question 7

What is the formula for bacteria fermentation?

Answer 7

Organic Molecule + NADH –> Reduced Organic Molecule + NAD⁺

Question 8

Where does ethanol fermentation occur?

Answer 8

in yeast