Cell Signalling and Transduction
Which of the following statements about G proteins is false?

They bind to and are regulated by guanine nucleotides
They must be active before the cell can make needed cAMP
They are involved in signal cascades
They become activated when bound to GDP

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Cell Signalling and Transduction
A signal cascade induced by adrenaline or thyroxine

must begin with receipt of the signal molecule by a surface receptor
All of these
results in the activation of a sequence of enzymes needed for the cell effect
involves the activation of a G protein

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Cell Signalling and Transduction
Why is it that inhaling nitric oxide reduces blood pressure only in the lung tissue and not elsewhere in the body*?

Because other body tissues use a different signaling molecule
Because nitric oxide breaks down quickly and thus cannot travel far
Because nitric oxide cannot cross cell membranes and enter the blood
None of these

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Cell Signalling and Transduction
Self-phosphorylation is an excellent mechanism for triggering specific catalytic function of the proteins involved in signal cascades because it

None of these
allows hydrophilic signaling molecules to cross the plasma membrane
makes the receptor more likely to capture the signaling, molecule
changes the shape and thus the enzymatic activity of the proteins involved

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Cell Signalling and Transduction
cAMP and cGMP are derived from

GTP and ATP by the actions of adenylate cyclase and guanylate cyclase respectively
ATP and GTP by the actions of adenylate cyclase and guanylate cyclase respectively
ATP and GTP by the actions of guanylate cyclase and adenylate cyclase respectively
None of these

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