• Pyruvate directly reduced by NADH
    • Result: NAD+ regeneration & ATP       Waste: lactate (no CO2)
  • In animals, lactic acid often transported to the liver to be turned into pyruvate when there is enough ATP

Fermentation vs Anaerobic vs Aerobic

  • Diff: methods of oxidizing NAD+, amount of ATP made
  • Same: all use glycolysis and NAD+ as oxidizing agent

Versatility of Catabolism

  • Glycolysis can break down diff macromolecules
    • Carbs, proteins, and fats give lots of energy bcuz of high energy electrons (C–H)
  • Carbs: all end up being hydrolyzed into glucose for glycolysis
  • Proteins: fuel, broken down into amino acids to make enzymes for cell respiration (biosynthesis/anabolic)
    • Eaten proteins are digested to amino acids; body proteins can be hydrolyzed to amino acids
    • Deamination: amino group leaves amino acid as waste so amino acid can enter cell R
    • Remainders of amino acids are converted into substances that act as intermediate step of glycolysis or krebs
  • Fats: digested to glycerol (for glycolysis) and and fatty acids (as Acetyl CoA in Krebs Cycle)
    • When fats are broken down they make more ATP than carbs and release CO2 & water
    • Beta Oxidation: breaks fatty acid chain into 2-C that directly enters Krebs

Regulation of Cellular Respiration

  • Controlled by allosteric enzymes at key points of glycolysis and citric acid cycle
  • ATP builds up → turns off phosphofructokinase (first enzyme in pathway) → stops glycolysis
    • Citrate also inhibits PFK
  • AMP turns back→ forces pathway on

Can speed up catabolic process: work hard + less ATP = more cell respiration