Question

Epinephrine and Glucose Let's assume that one mo lecule of epinephrine binding to the cell activates one G-protein, which activates one adenylate cyclase. From there, assume that every enzyme catalyzes 10 reactions (for example, each activated adenlylate cyclase produces 10 molecules of activated cAMP dependent protein kinase). Finally, assume that each activated glycogen phosphorylase rees" 10 molecules of glucose to be released from the cell into the bloodstream. 1. How many molecules of glucose are released into the blood for each molecule of epinephrine that binds? Consider that the epinephrine is only present when you see the jaguar, so prior to that there is no epinephrine to bind. After the epinephrine is in the bloodstream, the number of bound epinephrine reaches a maximum when all the receptors are full 2. Suppose that there are 100 epinephrine receptors on the cell. Write an equation for the amount of glucose as a function of the amount of bound epinephrine. 3. Plot the relationship between epinephrine bound and glucose released 1200000 1000000 800000 Glucose 600000 Released 400000 200000 0 0 20 4060 80 100 120 140 160 Epinephrine Bound 4. Explain what biological features of this system are responsible for the shape of the graph.

Answer 1

1) 1 molecule of epinephrine activates 1 molecule of adenylyl cyclase and it produces 10 molecules of cAMP.

10 molecules of cAMP activates 10 molecules of protein kinase A.

Each enzyme activates 10, therefore 10 molecules of protein kinase A activates 100 molecules of phosphorylase kinase and which then activates 1000 molecules of glycogen phosphorylase.

Finally, each glycogen phosphorylase frees 10 molecules of glucose, therefore 10,000 molecules of glucose are released into the blood.

Answer : For each molecule of epinephrine, 10,000 molecules of glucose are released into the blood.

2) Y is a function of X means that Y varies based on the value of X.

X = epinephrine, Y = Glucose

Equation for the amount of glucose as a function of the amount of bound epinephrine is Y = (X x 10³)

When, X = 1 (Epinephrine)

Y = (1 x 10³​) = 10, 000 molecules of glucose released

When, X = 100 (Epinephrine)

Y = (100 x 10³​) = 1,000, 000 molecules of glucose released