Acetylcholine acts at a GPCR on heart muscle to make the heart beat more slowly.
ID: 78339 • Letter: A
Question
Acetylcholine acts at a GPCR on heart muscle to make the heart beat more slowly. It does so by ultimately opening K+ channels in the plasma membrane (as diagrammed below), which decreases the cell’s excitability by making it harder to depolarize the plasma membrane. Explain HOW the following conditions would increase or decrease the effect of acetylcholine.
I know which ones increase or decrease but I am unsure on how the conditions cause this to happen.
A. addition of a drug that stimulates the GTPase activity of the G subunit
B. mutations in the K+ channel that keep it closed all the time
C. modification of the G subunit by cholera toxin
D. a mutation that decreases the affinity of the complex of the G protein for the K+ channel
E. a mutation in the acetylcholine receptor that prevents its localization on the cell surface
F. adding acetylcholinesterase to the external environment of the cell
ma membrane. Explain How the following ect of acetylcholine. Plama membrane g that stimulates the GTPase activity of the Ga K channel that keep it closed all the timeExplanation / Answer
question
Acetylcholine acts at a GPCR on heart muscle to make the heart beat more slowly. It does so by ultimately opening K+ channels in the plasma membrane (as diagrammed below), which decreases the cell’s excitability by making it harder to depolarize the plasma membrane. Explain HOW the following conditions would increase or decrease the effect of acetylcholine.
answer
Addition of a high concentration of a non-hydrolyzable analog of GTP that cannot be converted to GDP
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A. addition of a drug that stimulates the GTPase activity of the G subunit
--------- decrease.
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B. mutations in the K+ channel that keep it closed all the time decrease.
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C. modification of the G subunit by cholera toxin--increase
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D. a mutation that decreases the affinity of the complex of the G protein for the K+ channel----------- decrease.
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E. a mutation in the acetylcholine receptor that prevents its localization on the cell surface -------------- decrease.
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F. adding acetylcholinesterase to the external environment of the cell---- decrease.