Multiple Choice
The minute-to-minute blood flow through the capillary beds is determined by the __________.
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10. Cell Signaling
Introduction to Cell Signaling
Multiple Choice
Which of the following best describes the role of ion channels in cell signaling?
A
They act as enzymes that phosphorylate target proteins.
B
They transport large macromolecules into the cell via endocytosis.
C
They synthesize second messengers directly from ATP.
D
They allow specific ions to flow across the membrane in response to a signal, altering the cell's membrane potential.
Verified step by step guidance1
Understand the role of ion channels in cell signaling: Ion channels are specialized proteins embedded in the cell membrane that allow specific ions (e.g., Na⁺, K⁺, Ca²⁺, Cl⁻) to pass through the membrane in response to a signal, such as a ligand binding or a change in voltage.
Eliminate incorrect options: Ion channels do not act as enzymes that phosphorylate target proteins. This is the role of kinases, not ion channels.
Eliminate another incorrect option: Ion channels do not transport large macromolecules into the cell via endocytosis. Endocytosis involves vesicle formation, not ion channels.
Eliminate the third incorrect option: Ion channels do not synthesize second messengers directly from ATP. This is the role of enzymes like adenylyl cyclase, which converts ATP to cyclic AMP (cAMP).
Conclude the correct role: Ion channels allow specific ions to flow across the membrane in response to a signal, which can alter the cell's membrane potential and initiate downstream signaling events.
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