Summary of Glycolysis and Pyruvate Oxidation

Energy Efficiency in Glycolysis

• Glycolysis is not very energy efficient.
• Uses enzyme-controlled steps to break one glucose molecule.
• Produces 2 ATP, only 2.2% of glucose's potential energy.
• Some energy lost as thermal energy; most energy stored in 2 pyruvate and 2 NADH + H+.

Fate of Pyruvate

• If oxygen is present: pyruvate enters mitochondria, leading to production of 38 ATP.
• If oxygen is absent: fermentation occurs, producing ATP, lactic acid, or ethanol.

Pyruvate Oxidation

• Purpose: Prepares pyruvate for the Krebs cycle (citric acid cycle).
• Location: Mitochondrial matrix.
• Process:
  • Decarboxylation: removes a carbon atom from pyruvate as CO₂ waste, leaving a 2-carbon molecule.
  • Remaining 2-carbon molecule is oxidized, electrons picked up by NAD+, forming NADH (stores energy).
  • 2-carbon molecule attaches to coenzyme A (CoA), forming Acetyl-CoA, which enters the Krebs cycle next.