Which pathway is described as glycolysis that produces one ATP, two NADPH, and two pyruvate per glucose?

Which pathway is described as glycolysis that produces one ATP, two NADPH, and two pyruvate per glucose?

• A. Embden-Meyerhof pathway
• B. Krebs cycle
• C. Fermentation
• D. Entner-Doudoroff pathway

Answer: (D)

Entner-Doudoroff pathway is an alternative route that functions like a glycolysis variant used by some bacteria. Its balance of energy and reducing power is distinct from the classical glycolysis pathway: it produces a single net ATP per glucose, generates two pyruvate molecules, and yields reducing equivalents biased toward NADPH due to the NADP+-dependent steps. Here's how the pieces come together. Glucose-6-phosphate is oxidized by a NADP+-dependent step to form a 6-phosphogluconate, producing NADPH. That compound is dehydrated and then cleaved into pyruvate and glyceraldehyde-3-phosphate. The glyceraldehyde-3-phosphate is then processed further to pyruvate, with another NADP+-linked dehydrogenation step that also contributes to ATP production via substrate-level phosphorylation. Overall, you end up with two pyruvate molecules, one net ATP, and two NADPH per glucose. This combination—two pyruvate, one ATP, and two NADPH—matches the described pathway, distinguishing it from Embden-Meyerhof (classic glycolysis), which yields more ATP and different NADH/NADPH outcomes, and from the Krebs cycle or fermentation, which have different end products and energy profiles.

Entner-Doudoroff pathway is an alternative route that functions like a glycolysis variant used by some bacteria. Its balance of energy and reducing power is distinct from the classical glycolysis pathway: it produces a single net ATP per glucose, generates two pyruvate molecules, and yields reducing equivalents biased toward NADPH due to the NADP+-dependent steps.

Here's how the pieces come together. Glucose-6-phosphate is oxidized by a NADP+-dependent step to form a 6-phosphogluconate, producing NADPH. That compound is dehydrated and then cleaved into pyruvate and glyceraldehyde-3-phosphate. The glyceraldehyde-3-phosphate is then processed further to pyruvate, with another NADP+-linked dehydrogenation step that also contributes to ATP production via substrate-level phosphorylation. Overall, you end up with two pyruvate molecules, one net ATP, and two NADPH per glucose.

This combination—two pyruvate, one ATP, and two NADPH—matches the described pathway, distinguishing it from Embden-Meyerhof (classic glycolysis), which yields more ATP and different NADH/NADPH outcomes, and from the Krebs cycle or fermentation, which have different end products and energy profiles.