3.2 Pyruvate Oxidation

3.2 Aerobic Respiration: Pyruvate Oxidation

Overview of Cellular Respiration Stages

• Stages of Cellular Respiration:

  • Glycolysis

  • Pyruvate Oxidation

  • The Krebs Cycle

  • The Electron Transport Chain

Pathways Post-Glycolysis

• After Glycolysis:

  • If oxygen is available:

    • Proceed to:

      • Pyruvate Oxidation

      • Krebs Cycle

      • Electron Transport Chain (ETC) and Chemiosmosis

  • If oxygen is absent:

    • Undergoes:

      • Anaerobic Respiration or Fermentation

Pyruvate Oxidation: Key Steps

Step 1: Transport and Decarboxylation

• Transport Mechanism:

  • Pyruvate is transported from the cytosol to the mitochondrial matrix.

• Decarboxylation Process:

  • Pyruvate (a 3-carbon molecule) undergoes decarboxylation

    • Carboxyl group removal: CO2 is released, converting it into a 2-carbon molecule.

Step 2: Redox Reaction

• Oxidation of Pyruvate:

  • The remaining 2-carbon compound undergoes an oxidation reaction.

• NAD+ Reduction:

  • During the process, NAD+ is reduced to NADH, capturing high-energy electrons.

Step 3: Formation of Acetyl-CoA

• Coenzyme A Addition:

  • The oxidized 2-carbon molecule binds with Coenzyme A (CoA).

  • The resulting compound is Acetyl-CoA, which enters the Krebs Cycle.

Summary of Glycolysis and Subsequent Energy Production

• Overall Reaction:

  • From one glucose molecule (C6H12O6):

    • Produces:

      • 2 ATP from Glycolysis

      • 32 ATP from Krebs Cycle and ETC

    • Waste products:

      • 6CO2 (carbon dioxide)

      • 12H2O (water)

      • Energy in the form of ATP