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Multiple Choice
Fermentation is essentially glycolysis plus an extra step in which pyruvate is reduced to form lactate or alcohol and carbon dioxide. This last step __________.
A
removes poisonous oxygen from the environment
B
extracts a bit more energy from glucose
C
prevents pyruvate from accumulating
D
enables the cell to make pyruvate into substances it can use
E
enables the cell to recycle the reduced NADH to oxidized NAD+
Verified step by step guidance
1
Understand the process of glycolysis: Glycolysis is the first step in the breakdown of glucose to extract energy for cellular metabolism. It occurs in the cytoplasm and results in the production of pyruvate, ATP, and NADH.
Recognize the role of fermentation: Fermentation is an anaerobic process that allows cells to regenerate NAD+ from NADH, enabling glycolysis to continue producing ATP in the absence of oxygen.
Identify the extra step in fermentation: After glycolysis, pyruvate is reduced to form either lactate (in lactic acid fermentation) or ethanol and carbon dioxide (in alcoholic fermentation). This step is crucial for recycling NADH back to NAD+.
Understand the importance of recycling NAD+: The conversion of NADH to NAD+ is essential because NAD+ is a necessary cofactor for glycolysis. Without NAD+, glycolysis would halt, and the cell would be unable to produce ATP anaerobically.
Conclude the purpose of the last step: The reduction of pyruvate in fermentation enables the cell to recycle NADH to NAD+, ensuring a continuous supply of NAD+ for glycolysis, thus allowing the cell to produce energy anaerobically.