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Receptors Linked to a Channel Protein (Quiz 2)

Why are channels through membranes so important for nerve and muscle function? Both nerves and muscles rely on the rapid transmission of information and of signals for movement. The diffusion of chemical signals over any significant distance would be too slow to cause muscle contractions quickly enough to deal with the challenges of moving a large body in a complex environment. Electrical signals travel much more rapidly and the direction of the signal can be more easily controlled. The mechanism for generating and controlling electrical signals is the movement of charged material (ions) across cellular membranes in a limited area. The control of ion movement requires gated channels through the membrane that are specific for certain ions and either open or close (depending on the ion) in response to a change in electrical charge.

View the animation below, then complete the quiz to test your knowledge of the concept.

1The ligand for the sodium channel is

2The ligand binds to
A)the sodium channel directly.
B)the sodium channel indirectly with the help of G proteins.
C)the sodium channel only after ATP hydrolysis.
D)sodium ions directly.
E)sodium ions indirectly with the help of G proteins.

3Opening of the sodium channel
A)occurs only after ATP hydrolysis.
B)occurs with the help of G proteins.
C)allows the diffusion of Na+ ions out of the cell.
D)allows the diffusion of Na+ ions into the cell.
E)allows the entry of the ligand into the cell.

4The sodium channel is said to be voltage-gated.

5When the ligand is not bound, the sodium channel remains closed.

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