Name(s): Recitation section (day and time) and your TA's name 1. In order to prevent a futile cycle, glycogen synthesis and breakdown are reciprocally regulated. When insulin binds the cell surface receptor, glycogen synthesis is stimulated and glycogen breakdown is inhibited. a. Do the effects of insulin on glycogen synthesis and glycogen breakdown make sense in terms of physiology? Why or why not? DURING EXERCISE OR FASTING Glucagon (liver) or epinephrine (muscle and liver) Adenylate cyclase GDP GTP ATP Cyclic AMP Protein Protein kinase A kinase A Phosphorylase Phosphorylase Glycogen Glycogen kinase kinase synthase a synthase b Phosphorylase Phosphorylase (inactive) Glycogen Glycogen,-1 Glucose 1-phosphate Figure 21.19 Biochemistry, Seventh Edition 2012 W. H. Freeman and Company b. The diagram above shows a glucagon stimulating a signaling cascade. Name the three reactions in this cascade that require ATP as a substrate. c. Given that we protein phosphorylation reactions take place during the regulation of glycogen breakdown, what type of enzyme reaction do you think occurs in the insulin signal cascade? Explain