Krebs Cycle

• Krebs cycle


  The second stage of aerobic respiration, which occurs within the matrix of the mitochondria
• Krebs cycle


  Also commonly referred to as the citric acid cycle or the tricarboxylic acid (TCA) cycle
• Krebs cycle


  1. Acetyl CoA transfers its acetyl group to a 4C compound (oxaloacetate) to make a 6C compound (citrate)

  2. Coenzyme A is released and can return to the link reaction to form another molecule of acetyl CoA

  3. Over a series of reactions, the 6C compound is broken down to reform the original 4C compound (hence, a cycle)

  4. Two carbon atoms are released via decarboxylation to form two molecules of carbon dioxide (CO2)

  5. Multiple oxidation reactions result in the reduction of hydrogen carriers (3 × NADH + H+; 1 × FADH2)

  6. One molecule of ATP is produced directly via substrate level phosphorylation
• As the link reaction produces two molecules of acetyl CoA (one per each pyruvate), the Krebs cycle occurs twice</b>
• Per glucose molecule, the Krebs cycle produces: 4 × CO2; 2 × ATP; 6 × NADH + H+; 2 × FADH2