Question 3: A runner just finished a marathon.For the enzymes listed below, indicate whether the enzyme activity is upregulated (1) ordownregulated (↓) in the muscle and liver, respectively.Enzyme(a) Glycogen synthase(b) Phosphofructokinase-1(c) Fructose-Bisphosphatase-2(d) Pyruvate kinase(e) Pyruvate carboxylase(f) Acetyl-CoA carboxylaseMuscleLiver

During the marathon, the runner required extra glucose in the blood for physical activity. Epinephrine causes the breakdown of glycogen into glucose (glycogenolysis) in muscle cells of runner. While, glucagon hormone is released from pancreas that causes the glycogenolysis into glucose in the liver. Epinephrine and glucagon acts opposite to that of insulin. cAMP works as a second messenger for epinephrine (liver and muscle) and glucagon (liver). Sequence of activity will be - Epinephrine (liver and muscle) or glucagon (liver) -- adenylate kinase -- cAMP -- Protein kinase (PKA) --Phosphorylase kinase --- Glycogen phosphorylase (phosphorylated form is active active)a. Glycogen synthase - it is an enzyme of glycogenesis (glycogen synthesis). it will be downregulated in liver as the demand of glucose in increased for runner just after the marathon while, the demand of glucose will be paused in muscle cells and eventually glycogen synthase will be upregulated. b. Phosphofructokinase - 1 (PFK-1) - it is an regulatory enzyme of 3rd step of glycolysis, in muscle cells it will be downregulated as the demand of energy is declined just after the marathon. Also, it will be downregulated in liver cells to cover up the demand of blood glucose level in the body. c. Fructose Bisphosphatase-2 (FBPase-2) - it is an enzyme which catalyzes Fructose 2,6 bisphosphate into Fructose 6-phosphate. FBPase-2 is inactive in fed state to activates the glycolysis and downregulates the gluconeogenesis. While, FBPase-2 is active in starve state to downregulates the glycolysis and activates the gluconeogenesis. Thus, FBP-2 will be downregulated in muscle cells as glucose level will be optimum in muscle cells of runner just after the marathon. Whereas, FBPase-2 will be upregulated in liver cells as glucose level will be dropped and gluconeogenesis occurs. d. Pyruvate kinase - it is an enzyme of the last step and regulatory step of glycolysis, in muscle cells it will be downregulated as the demand of energy is declined just after the marathon. Also, it will be downregulated in liver cells to meet the demand of blood glucose level in the body. e. Pyruvate carboxylase - it catalyzes the carboxylation of pyruvate with formation of oxaloacetate which is an important anaplerotic reaction. it catalyzes an important step of gluconeogenesis. It will be downregulated in liver as to meet the demand optimum blood glucose. While, it will be upregulated in muscle cells as energy demand is declined just after the marathon and gluconeogenesis should be upregulated. f. Acetyl co A carboxylase - it catalyzes the carboxylation of acetyl co A to malonyl co A, which is an irreversible step for the biosynthesis of fatty acids. In muscle cells, it will be upregulated as the demand of energy is declined just after the marathon. However, it will be downregulated in liver cells to meet the demand of blood glucose level in the body via gluconeogenesis.