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Senanu's Bio class

Chapter 9.1-9.4 – Glycolysis and the Citric Acid Cycle

OBJECTIVE: Understand what a redox reaction is. OBJECTIVE: recognize that in general, high-energy compounds are the reduced form. As they are oxidized, their energy level drops.

  1. Describe how respiration can be viewed as the opposite of photosynthesis.
  2. What is the full, summary equation for cellular respiration?
  3. Is respiration endergonic or exergonic? What is the sign on ΔG?
  4. What is a redox reaction?
  5. A substance that gains an electron is: _________________
  6. A substance that loses an electron is: _________________
  7. Look at the summary equation for respiration in the text of chapter 9.1. What is the oxidized form – oxygen or water?
  8. Which is the reduced form of carbon – glucose or carbon dioxide?
  9. What is the reduced form – NAD+ or NADH? (see chapter 8)
  10. Based on your previous 3 answers, does the oxidized or reduced form of a compound contain more energy?

  11. What is the ‘function’ of NAD+ with regard to electrons?

    OBJECTIVE: Understand that catabolic and anabolic pathways for fats and proteins are linked by glycolysis and the citric acid cycle

  12. What is the difference between anabolism and catabolism (Fig 9.3)?
  13. What happens to proteins before they can enter the catabolic pathway?

  14. Fatty acids join the catabolic pathway as acetyl CoA, essentially a 2 carbon compound. Consider the number of turns of the citric acid cycle to help explain why fats are such energy-rich foods.

    OBJECTIVE: Describe how the carbon skeleton of glucose changes as it proceeds through glycolysis. OBJECTIVE: Distinguish between the energy investment phase and the energy payoff phase of glycolysis.

  15. Place the following processes in order:
    • Pyruvate oxidation
    • Electron transport
    • Glycolysis
    • Citric acid cycle
  16. Why is the first portion of glycolysis referred to as the energy investment phase?
  17. How is the energy investment phase of glycolysis different from the energy payoff phase of glycolysis?
  18. Is oxygen required for glycolysis?
  19. List the reactants of glycolysis.
  20. List the products of glycolysis.
  21. Look at the reactions of glycolysis. Which require ATP? For each molecule of glucose, how many ATP are required?
  22. Which reactions of glycolysis produce ATP? How many ATP are produced per molecule of glucose?
  23. Which reaction is a redox reaction? State which molecule was reduced and which was oxidized. As a hint, think about an additional molecule that you’re already learned about that carries electrons. When it carries electrons, it is the reduced form, and the other molecule is the oxidized form.
  24. Look at the names of the enzymes required for each step of glycolysis. What suffix do they all have? How is the name of the enzyme related to the reaction it catalyzes? (Hint: kinases transfer phosphate groups between molecules.)

  25. Describe substrate-level phosphorylation. Keep this in mind as you will later compare it with oxidative phosphorylation.

    OBJECTIVE: Describe where pyruvate is oxidized to acetyl CoA, what molecules are produced, and how this process links glycolysis to the citric acid cycle.

  26. How many membranes does pyruvate have to cross to enter the matrix of the mitochondria? Show this in a diagram.
  27. Your book states that pyruvate enters the mitochondria by active transport. Does this require energy? How do you know?

  28. List the products of pyruvate oxidation.

    OBJECTIVE: List the products of the citric acid cycle.
    OBJECTIVE: Summarize the net ATP yield from the oxidation of a glucose molecule by constructing an ATP ledger.

  29. Look at figure 9.10. Identify which reactions are redox reactions.
  30. How many of each of the following molecules are produced by the combination of glycolysis, pyruvate processing, and the citric acid cycle?
    • ATP
    • NADH
    • FADH2

    OBJECTIVE: Understand how feedback regulation controls the rate of cellular respiration

  31. What is the name of the enzyme that is regulated by ATP?
  32. Which step of glycolysis does this happen in?
  33. Is this regulation competitive or allosteric? Explain what this means.
  34. What happens to the rate of ATP production if the cell has ample ATP?