How many NADH are produced by glycolysis?
A. 4
B. 3
C. 2
D. 5
E. 1
Answer (2)
Glycolysis produces a total of 2 NADH molecules for each molecule of glucose processed. This occurs during the conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate. Thus, the correct answer is C. 2.
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Glycolysis converts glucose to pyruvate, producing ATP and NADH.
NADH is generated during the oxidation of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate.
Two molecules of glyceraldehyde-3-phosphate are formed per glucose molecule, leading to two NADH molecules produced.
Therefore, glycolysis produces 2 NADH molecules.
Explanation
Problem Analysis We are asked to determine the number of NADH molecules produced during glycolysis. Glycolysis is a metabolic process that breaks down glucose into pyruvate, generating ATP and NADH.
NADH Production Step Glycolysis consists of several steps, and NADH is produced in one key step: the oxidation of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate. In this reaction, glyceraldehyde-3-phosphate dehydrogenase uses NAD+ to produce NADH.
Stoichiometry of NADH Production For each molecule of glucose that enters glycolysis, two molecules of glyceraldehyde-3-phosphate are formed. Therefore, this reaction occurs twice per glucose molecule. Each time it occurs, one molecule of NAD+ is reduced to one molecule of NADH.
Total NADH Production Since the reaction occurs twice for each glucose molecule, a total of 2 NADH molecules are produced during glycolysis.
Final Answer Therefore, the number of NADH molecules produced by glycolysis is 2 .
Examples
Understanding NADH production in glycolysis is crucial in exercise physiology. During intense physical activity, muscles rely heavily on glycolysis for energy. The NADH produced must be re-oxidized to NAD+ to sustain high rates of glycolysis. This is achieved through the electron transport chain in mitochondria under aerobic conditions, or through lactate dehydrogenase in anaerobic conditions, allowing athletes to maintain energy production during strenuous activities.
