Which metabolic pathway converts glucose into two pyruvate molecules?

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Multiple Choice

Which metabolic pathway converts glucose into two pyruvate molecules?

Glycolysis is the process that takes a six-carbon glucose and splits it into two three-carbon pyruvate molecules in the cytosol. It yields a net gain of two ATP and two NADH per glucose, and it operates whether or not oxygen is present. The pathway has an energy-investment phase and an energy-payoff phase, with the rate-limiting step at the phosphorylation of fructose-6-phosphate by phosphofructokinase-1, a major control point that matches glucose breakdown to the cell’s energy needs. In aerobic conditions, the two pyruvate molecules can be further processed in mitochondria to acetyl-CoA and enter the citric acid cycle, extracting more energy. In anaerobic conditions, pyruvate is reduced to lactate to regenerate NAD+, allowing glycolysis to continue producing ATP. Other listed pathways do different things: gluconeogenesis makes glucose from noncarbohydrates; glycogenolysis breaks down glycogen to glucose units; the pentose phosphate pathway generates NADPH and ribose-5-phosphate, not pyruvate. The reason glycolysis is the correct answer is that only this pathway converts glucose directly into two molecules of pyruvate.

Glycolysis is the process that takes a six-carbon glucose and splits it into two three-carbon pyruvate molecules in the cytosol. It yields a net gain of two ATP and two NADH per glucose, and it operates whether or not oxygen is present. The pathway has an energy-investment phase and an energy-payoff phase, with the rate-limiting step at the phosphorylation of fructose-6-phosphate by phosphofructokinase-1, a major control point that matches glucose breakdown to the cell’s energy needs.

In aerobic conditions, the two pyruvate molecules can be further processed in mitochondria to acetyl-CoA and enter the citric acid cycle, extracting more energy. In anaerobic conditions, pyruvate is reduced to lactate to regenerate NAD+, allowing glycolysis to continue producing ATP.

Other listed pathways do different things: gluconeogenesis makes glucose from noncarbohydrates; glycogenolysis breaks down glycogen to glucose units; the pentose phosphate pathway generates NADPH and ribose-5-phosphate, not pyruvate. The reason glycolysis is the correct answer is that only this pathway converts glucose directly into two molecules of pyruvate.

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