Chapter 17

Marathon runners preparing for a race engage in "carb loading" to maximize their carbohydrate reserves. This involves eating large quantities of starchy foods. Why is starch preferable to candy or sugar-rich foods?

Proteolysis increases during the early phases of fasting, but later it decreases as the body adapts to using alternative energy sources. Given that feedback control mechanisms have not been described for intracellular proteases, how might you explain these apparent changes in protease activity?

Adipose tissue cannot resynthesize triacylglycerols from glycerol released during lipolysis (fat breakdown). Why not? Describe the metabolic route that is used to generate a glycerol compound for triacylglycerol synthesis.

(a) Briefly describe the relationship between intracellular malonyl-CoA levels in the liver and the control of ketogenesis. (b) Describe how the action of hexokinase IV helps the liver to buffer the level of blood glucose.

The action of glucagon on liver cells leads to inhibition of pyruvate kinase. What is the most probable mechanism for this effect?

AMPK and mTOR can both be considered intracellular signal integrators. Explain this definition.