Apentix/AP Biology/Ap bio u4/Question
AP Biologyhardmcq1 pt

In a study on the effects of caffeine on cell signaling pathways, researchers find that caffeine inhibits the activity of protein kinase A (PKA). Based on this information, which of the following is a likely explanation for caffeine's effect?

A.D) Caffeine has no effect on the cAMP signaling pathway and PKA activity.
B.C) Caffeine inhibits the activity of phosphodiesterase, increasing cAMP levels and activating PKA.
C.B) Caffeine blocks the action of G-proteins, preventing the activation of PKA.
D.A) Caffeine activates the cAMP signaling pathway, leading to increased activity of PKA.

Explanation

Core Concept

Caffeine acts as a phosphodiesterase inhibitor, increasing cAMP levels and activating PKA. This is a key step in the cAMP signaling pathway, which is involved in various cellular processes including gene expression and metabolism. (Concept: Signal Transduction) The primary reason this is true is that phosphodiesterase inhibitors increase cAMP levels, which in turn activate PKA.

Correct Answer

C

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