Topic 3: Pyruvate Oxidation

Pyruvate Oxidation

• The pyruvate molecules produced during glycolysis are transported through the mitochondrial membranes into the mitochondrial matrix
  • Occurs via active transport
• Here the pyruvate undergoes three changes:
  • A molecule of CO2 is removed from pyruvate
  • Decarboxylation reaction
  • A redox reaction occurs where the 2-carbon portion of the pyruvate is oxidized while NAD+ is reduced to NADH
  • Coenzyme A (sulphur-containing, nonprotein organic molecule) is attached to the 2-carbon compound to produce acetyl-CoA
• Overall equation: 2 pyruvate + 2 NAD+ → 2 acetyl-CoA + 2 NADH + 2 H+ + 2 CO2
  • 2 molecules of CO2 produced, diffuse out of mitochondrion and into the cytoplasm to be taken out of the cell as waste
  • 2 NADH proceed to next stage of cellular respiration
  • 2 H+ ions dissolve into the matrix
• If the cell is in need of energy (low ATP), the acetyl-CoA enters a cyclic process called the Krebs cycle
• Occurs in mitochondrial matrix
• If the cell has high ATP, the acetyl-CoA becomes involved in another series of reactions that produce lipids in order to store the excess energy
  • Causes weight gain
  • Pyruvate → Acetyl CoA is catalyzed by a multi-enzyme complex called pyruvate dehydrogenase complex