IB BIO - U2L16P2 - Anaerobic Respiration + Respective Theoretical Yield.

Stage 1 of Aerobic Respiration.

• Glycolysis.

  • Glucose →Pyruvate

    • Produces:

      • 2 NADH

      • 2 ATP

Stage 2a of Anaeerobic Respiration.

• Lactic Acid Fermentation.

  • (2) Pyruvate →(2) Lactic Acid

    • Produces:

      • 2 NAD+

        • NAD+ is to be replenished to propagate the cycle via glycolysis.

        • In animals, this occurs via a reversible process dubbed lactic acid fermentation.

    • If oxygen is available this process goes into pyruvate oxidation.

    • 2 ATP/Glucose molecule is produced.

    • Lactic acid (lactate) is a toxic byproduct.

Lactic Acid and Exercise

• During intense exercise, cell energy demands exceed what oxygen gas can readily supply aerobically.

  • After exercise, oxygen levels will increase and lactate will be converted back to pyruvate.

• Body maximises ATP yield by anaerobic respiration of glucose too.

  • Only Carbohydrates typically undergo anaerobic respiration.

Stage 2b of Aerobic Respiration.

• Alcohol Fermentation.

  • (2) Pyruvate →(2) CO2

    • Produces:

      • 2 NAD+

        • NAD+ is to be replenished to propagate the cycle via glycolysis.

        • In plants and yeast, this occurs via a reversible process dubbed alcohol fermentation.

        • The conversion of pyruvate to lactic acid involves the transfer of electrons from NADH to pyruvate.

        • This electron transfer regenerates NAD+ from NADH.

    • If oxygen is available this process goes into pyruvate oxidation.

    • 2 ATP/Glucose molecule is produced.

    • Lactic acid (lactate) is a toxic byproduct.

Anaerobic vs. Aerobic Respiration.

• Reactants.

  • Anaerobic

    • Glucose.

  • Aerobic

    • Glucose.

    • Oxygen.

• Combustion.

  • Anaerobic.

    • Incomplete.

  • Aerobic

    • Combustion.

• Energy Yield.

  • Anaerobic.

    • Low (2 ATP)

  • Aerobic

    • High (36 - 38 ATP)

• Products.

  • Anaerobic

    • Animals: Lactic Acid.

    • Yeast + Plants: Ethanol + CO2

  • Aerobic

    • CO2 and H2O

• Location.

  • Anaerobic.

    • Cytoplasm.

  • Aerobic.

    • Cytoplasm.

    • Mitochondrion.

• Stages.

  • Anaerobic.

    • Glycolysis.

    • Fermentation.

  • Aerobic

    • Glycolysis

    • Link Reaction

    • Krebs Cycle

    • Electron Transport Chain

Types of Aerobic Reactions.

• Decarboxylation.

  • Decarboxylation involves the removal of a carbon dioxide (CO2) molecule from a compound. In the context of aerobic reactions, decarboxylation often occurs in the citric acid cycle (Krebs cycle) during cellular respiration.

  • During the Krebs cycle, decarboxylation reactions lead to the release of CO2, contributing to the overall breakdown of glucose and the generation of energy.

• Oxidation.

  • Oxidation is a chemical process that involves the loss of electrons or an increase in oxidation state. In cellular respiration, oxidation reactions are central to the transfer of electrons from energy-rich molecules (like glucose) to electron carriers (such as NAD+ and FAD), ultimately leading to the production of ATP.

  • The ETC, which is a key part of aerobic respiration, involves a series of oxidation-reduction reactions.

• Phosphorylation.

  • Phosphorylation involves the addition of a phosphate group to a molecule. In cellular respiration, phosphorylation is a key step in the generation of ATP.

    • Oxidative phosphorylation:

      • Occurs in the ETC, where the flow of electrons through protein complexes is coupled to the phosphorylation of ADP to ATP.