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What Enters the Krebs Cycle

publish date: 2026/06/21 09:14:16.038162 UTC

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Aerobic Respiration Stage II & III Mitochondrial Matrix Pathways & Electron Transport Chain Pyruvate (3-Carbon) +CoA & NAD⁺ → NADH Releases CO₂ Acetyl-CoA (2-Carbon) Joins OAA (4C) KREBS CYCLE (Matrix) Outputs: CO₂ Produces: 2 ATP High-Energy Electron Carriers NADH and FADH₂ Donate electrons to Cristae membrane Electron Transport Chain (Mitochondrial Cristae Membranes) Stepwise oxidation via cytochromes drives H⁺ proton pumping Chemiosmosis (via ATP Synthase) Yields ~28 to 32 ATP Final Electron Acceptor ½ O₂ + 2H⁺ + 2e⁻ → H₂O Summary: Total Aerobic yield nets around 32-36 ATP per Glucose completely oxidized.

Based on the diagram, what molecule, formed when coenzyme A attaches to acetate, enters the Krebs cycle?

Correct Answer

Acetyl-CoA

Explanation

Pyruvate is first converted into the 2-carbon compound acetate, which then combines with coenzyme A to form acetyl-CoA. This is the molecule that actually enters and fuels the Krebs cycle.

Reference

Biology: A self-teaching guide

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