Problem 1
Why is it essential that the mechanisms that activate glycogen synthesis also deactivate glycogen phosphorylase?
Problem 2
How does phosphorolysis differ from hydrolysis?
Problem 3
Why is it advantageous that breakdown of glycogen gives rise to glucose- 6 -phosphate rather than to glucose?
Problem 4
Briefly outline the role of UDPG in glycogen biosynthesis.
Problem 9
You are planning to go on a strenuous hike and are advised to eat plenty of high-carbohydrate foods, such as bread and pasta, for several days beforehand. Suggest a reason for the advice.
Problem 12
The concentration of lactate in blood rises sharply during a sprint and declines slowly for about an hour afterward. What causes the rapid rise in lactate concentration? What causes the decline in lactate concentration after the run?
Problem 14
What is the source of the energy needed to incorporate glucose residues into glycogen? How is it used?
Problem 17
What is the effect on gluconeogenesis and glycogen synthesis of (a) increasing the level of ATP, (b) decreasing the concentration of fructose- \(1,6-\) bisphosphate, and (c) increasing the concentration of fructose- 6 -phosphate?
Problem 19
Suggest a reason why sugar nucleotides, such as UDPG, play a role in glycogen synthesis, rather than sugar phosphates, such as glucose- 6 -phosphate.
Problem 21
Which steps of glycolysis are irreversible? What bearing does this observation have on the reactions in which gluconeogenesis differs from glycolysis?
