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12. Energy and Respiration

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  1. 12.1 Energy

    1. 12.1.1Energy needs in living organisms

      • Energy needs in living organisms: active transport, movement, anabolic reactions (DNA replication, protein synthesis)

    2. 12.1.2ATP features as universal energy currency

      • ATP features as universal energy currency

    3. 12.1.3ATP synthesis

      • ATP synthesis: - Substrate-linked reactions - Chemiosmosis in mitochondria and chloroplast membranes

    4. 12.1.4Energy values of respiratory substrates

      • Relative energy values: carbohydrates, lipids, proteins as respiratory substrates

    5. 12.1.5Respiratory quotient (RQ)

      • Respiratory quotient (RQ): ratio of CO2 produced to O2 taken in

    6. 12.1.6RQ calculations

      • Calculate RQ values from respiration equations

    7. 12.1.7Respirometer investigations

      • Investigate using respirometers: determine RQ of germinating seeds or invertebrates

  2. 12.2 Respiration

    1. • Four stages of aerobic respiration location: - Glycolysis: cytoplasm - Link reaction: mitochondrial matrix - Krebs cycle: mitochondrial matrix - Oxidative phosphorylation: inner mitochondrial membrane

    2. • Glycolysis: phosphorylation of glucose, splitting of fructose 1,6-bisphosphate (6C) into two triose phosphates (3C), oxidation to pyruvate (3C), producing ATP and reduced NAD

    3. • Pyruvate enters mitochondria for link reaction when oxygen available

    4. • Link reaction: role of coenzyme A in acetyl (2C) group transfer

    5. • Krebs cycle: oxaloacetate (4C) accepts 2C from acetyl coenzyme A to form citrate (6C), converted back to oxaloacetate

    6. • Krebs cycle involves decarboxylation, dehydrogenation, reduction of NAD and FAD

    7. • NAD and FAD transfer hydrogen to inner mitochondrial membrane carriers

    8. • Oxidative phosphorylation: - Hydrogen splits into protons and energetic electrons - Electrons release energy through electron transport chain - Energy transfers protons across inner mitochondrial membrane - Protons return via ATP synthase by facilitated diffusion, providing energy for ATP synthesis - Oxygen as final electron acceptor forms water

    9. • Mitochondria structure-function relationship

    10. • Anaerobic respiration: lactate fermentation (mammals), ethanol fermentation (yeast)

    11. • Energy yield: aerobic >> anaerobic respiration

    12. • Rice adaptations: aerenchyma in roots, ethanol fermentation, faster stem growth

    13. • Investigate using redox indicators (DCPIP, methylene blue): effects of temperature and substrate concentration on yeast respiration rate

    14. • Investigate using respirometers: temperature effects on respiration rate