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 become activated when bound to GDP
They bind to and are regulated by guanine nucleotides
They are involved in signal cascades

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Cell Signalling and Transduction
cAMP and cGMP are derived from

None of these
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

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

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