4.2 - Pyruvate Oxidation and the Citric Acid Cycle

• NAD+ and NADH - Nicotinamide adenine dinucleotide

  • NAD+ can be reduced to form NADH
  • NADH can be oxidized to donate electrons
• FAD and FADH2 - Flavin adenine dinucleotide

  • FAD can be reduced to form FADH2
  • FADH2 can be oxidized to donate electrons
• GTP: = guanosine triphosphate.

  • can be used to generate ATP
• Pyruvate Oxidation and the Citric Acid Cycle help to harvest the remaining available energy
• The 2 molecules of Pyruvate that are synthesized by Glycolysis still contain most of the energy stored in glucose
• What happens during Pyruvate Oxidation?


  1. Carboxyl Group is removed -- creates CO2
  2. NAD+ steals electrons from remaining molecule to become NADH
  3. Coenzyme A attaches to molecule to form Acetyl CoA

  
• Reaction of Pyruvate Oxidation:

  2 Pyruvate + 2 NAD+ + 2 CoA

  ==> 2 Acetyl CoA + 2 NADH + 2 H+ + 2 CO2
• The Citric Acid Cycle

  • consists of 8 enzyme catalyzed reaction
  • used to create energy carrier molecules (NADH and FADH2)
  • creates 2 ATP (1 per pyruvate)
  • converts the remaining carbon from pyruvate into CO2
• The Citric Acid Cycle keeps moving because oxaloacetate ( the first reactant) is regenerated
• Every step is catalyzed by reactions
• GTP (guanine triphosphate) is used to make ATP
• NADH and FADH2 will be used later to make ATP