Metabolic Pathways

Glycolysis Pathway

Input: 1 Glucose

Outputs:

  • 2 Pyruvate
  • 2 ATP (net)
  • 2 NADH

β-Oxidation

Input: 1 Palmitic Acid (C16)

Outputs per cycle:

  • 8 Acetyl-CoA
  • 7 FADH2
  • 7 NADH

Krebs Cycle

Input: 1 Acetyl-CoA

Outputs per cycle:

  • 2 CO2
  • 6 NADH
  • 2 FADH2
  • 2 ATP

Electron Transport Chain

Inputs:

  • NADH → 3 ATP
  • FADH2 → 2 ATP
  • O2 (final electron acceptor)

Outputs:

  • H2O
  • ATP

Total ATP Yield Comparison

SubstrateProcessATP Yield
GlucoseAnaerobic2 ATP
GlucoseAerobic~36-38 ATP
Palmitic Acidβ-oxidation + Krebs~129 ATP

Lactate Metabolism

Production:

  • Pyruvate → Lactate + H⁺
  • Occurs when oxygen is limited
  • Allows glycolysis to continue

Clearance:

  • Cori Cycle (liver conversion back to glucose)
  • Direct oxidation in muscle cells
  • Conversion back to pyruvate