What happens during Krebs cycle?

During the Krebs cycle, acetyl-CoA (2C) combines with oxaloacetate (4C) to form citrate (6C). Citrate undergoes isomerization to isocitrate, followed by sequential oxidative decarboxylations, producing two CO₂ molecules and reducing three NAD⁺ to NADH and one FAD to FADH₂. A GTP (or ATP) is also generated through substrate-level phosphorylation. The cycle regenerates oxaloacetate in its final step, enabling it to initiate another round. The reduced cofactors carry high-energy electrons to the electron transport chain, which drives ATP synthesis via oxidative phosphorylation.