The Biology Project > Cell Biology > Cell Signaling > Problem Set

Cell Signaling Problem Set

Problem 10: Signaling Events

Tutorial to help answer the question

In a fight-or-flight response, epinephrine released by the adrenal glands binds to a membrane receptor on muscle cells. Which of the following events result from ligand binding?

A.	G-protein is activated by binding GTP and causing adenylyl cyclase to produce cAMP.
B.	The second messenger, cAMP, activates protein kinase A which inhibits glycogen synthetase blocking glycogen synthesis.
C.	Protein kinase A activates phosphorylase kinase, which transfers a phosphate that activates glycogen phosphorylase. This leads to the breakdown of glycogen and the production of glucose-1-phosphate.
D.	Glucose produced from glucose-1-P stimulates glycolysis, producing energy for muscle contraction.
E.	All of the above.

Tutorial

Signaling events

The cascade of enzyme activations and inhibitions results in the release of glucose into our blood from our liver and the breakdown of stored glycogen in our muscle. The activation of glycolysis increases the supply of ATP available for muscle contraction.

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