The Biology Project
Cell Signaling > 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?
| Answer | Problem 11
||G-protein is activated by binding GTP and causing
adenylyl cyclase to produce cAMP.
||The second messenger, cAMP, activates protein kinase
A which inhibits glycogen synthetase blocking glycogen synthesis.
||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.
||Glucose produced from glucose-1-P stimulates glycolysis,
producing energy for muscle contraction.
||All of the above.
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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