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Senanu's Bio class

Chapter 9.5 – Chemiosmosis and the Electron Transport Chain

OBJECTIVE: Summarize the net ATP yield from the oxidation of a glucose molecule by constructing an ATP ledger.

  1. Fill out the following table

    STAGE OF CELLULAR
    RESPIRATION    		 LOCATION
    IN CELL    		 STARTING
    MOLECULES    		 MOLECULES
    PRODUCED    		 SUMMARY OF STAGE
    Glycolysis Splits glucose molecule
    in two and harvests a little
    energy from glucose
    Pyruvate Oxidation Pyruvate
    Citric Acid Cycle NADH
    FADH2
    CO2
    ATP
    Oxidative
    Phosphorylation    		 Mitochondria
    Inner Membrane

    OBJECTIVE: Explain where and how the respiratory electron transport chain creates a proton gradient.

  2. Look back at Figure 8.7.
    • Write the reversible reaction between NAD+ and NADH. Label which is the reduced form and which is the oxidized form. Label the arrows with exergonic and endergonic.
    • Which form (NAD+ or NADH) is the high-energy form (ie which has more potential energy)?

  3. How do electrons enter the electron transport chain (ETC)?

    OBJECTIVE: Explain how the exergonic “slide” of electrons down the electron transport chain is coupled to the endergonic production of ATP by chemiosmosis. OBJECTIVE: Explain why this gradient is described as a proton motive force.

  4. What is the basic ‘job’ of the ETC? (What do protein complexes I, III, and IV do?)
  5. As electrons move through the electron transport chain, they move from molecules with _____________ (lower or higher) electronegativity to molecules with ______________(lower or higher) electronegativity. Finally, they are combined with Oxygen, which has the ______________(highest or lowest) electronegativity.
  6. The proton pumps of the ETC pump protons into what part of the mitochondria?
  7. What is meant by a ‘proton gradient’?
  8. Why do protons ‘want’ to get back into the inner region (matrix) of the mitochondria?
  9. What path do protons find to get back into the mitochondrial matrix? What happens as they take this route back to the matrix?
  10. Why is oxygen so important for the ETC? What do you think would happen without it (also, try holding your breath forever!)
  11. Look at figures 9.14. Which electron carrier do you think causes more protons to be pumped into the intermembrane space. How do you know?
  12. Look at the pictures of mitochondria in Figure 7.13. What advantage does having the inner membrane of the mitochondria “highly folded and wrinkled”? (Hint: what does wrinkling do to the surface area and why would this be beneficial?)
  13. What category of molecule is ATP synthase?
  14. What is the function of ATP synthase?
  15. Describe the similarity between ATP synthase shown in Fig 9.18 and a hydroelectric turbine.
  16. Is the generation of ATP by ATP synthase endergonic or exergonic? What powers ATP synthase?
  17. What is chemiosmosis? What is the Proton-motive force? Compare this to a dam on a river.
  18. The generation of ATP by ATP Synthase is known as oxidative phosphorylation. What term is used to describe the direct production of ATP such as during glycolysis?
  19. If you were to radioactively label the oxygen you were breathing in, what molecule would become radiolabeled as a result of cellular respiration? (hint, it’s not CO2)
  20. If ALL of the proton-motive force generated by the electron transport chain was used to drive ATP production, how many ADP molecules could be photosphorylated to ATP?