Reading Guide, Pratt and Cornely Chapter 13b
1. In what tissue does the gluconeogenesis pathway generally take place? What is the purpose of gluconeogenesis? When is it necessary?
2. Why can’t gluconeogenesis be simply the exact reverse of the glycolysis pathway?
3. Draw the reactions that produce phosphoenolpyruvate from pyruvate. How much energy is expended in this process?
4. What are the names of the two enzymes that catalyze the opposite reactions of phosphofructokinase and hexokinase?
5. If a molecule of glucose runs through glycolysis and then back through gluconeogenesis, what is the net ATP cost? What is the mechanism by which this “futile cycle” is regulated?
6. How is glucose stored in liver and muscle cells? Is energy required to polymerize glucose or to depolymerize glucose?
7. Write the three reactions needed to incorporate glucose-1-phosphate into glycogen. What is the net reaction? What is the net cost in ATP equivalents?
8. Glycogen phosphorylase doesn’t release glucose from glycogen by hydrolysis, but rather by
______________. Ultimately, this conserves ATP energy because the glucose released from glycogen can skip which step in glycolysis?
9. Which enzyme in glycogen synthesis/degradation is highly regulated? Does this make sense?
10. Name three enzymes we have studied that cause glycogen storage disease if mutated.