Kreb cycle

• Occurs in mitochondrial matrix

  • Acetyl coenzyme A reacts with a 4-carbon molecule (oxaloacetate), producing a 6-carbon molecule (citrate) that enters the Krebs cycle

  • Coenzyme A released

  • 6C molecule 5C 4C molecule (4C molecule regenerated) through a series of oxidation-reduction reactions...

  • Decarboxylation and dehydrogenation

  • CO 2 removed

  • Coenzymes NAD & FAD reduced (key point – important for oxidative phosphorylation)

  • ATP produced by substrate level phosphorylation (direct transfer of P i from intermediate compound to ADP)

  
• Acetyl coenzyme A combines with a 4-carbon molecule to form a 6-carbon molecule.
• The 5-carbon molecule is converted back into the original 4-carbon molecule, forming one CO2, two NADH from NAD, one ATP from ADP + Pi, and one FADH from FAD.
• FAD is a coenzyme like NAD but with a slightly different structure though it has a similar function.
• The ATP, NADH and FADH move on to the next stage of respiration while the 4-carbon molecule combines with another acetyl coenzyme A and carries out the cycle again.