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

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

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

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

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

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Cell Signalling and Transduction
The binding of ligands to many G-proteins linked receptors leads to shortlived

decrease in the concentration of certain extracellular signaling molecules called first messenger
decrease in the concentration of certain intracellular signaling molecules called second messenger
increase in the concentration of certain intracellular signaling molecules called second messenger
increase in the concentration of certain extracellular signaling molecules called first messenger

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