- 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