Cell Signalling and Transduction
cAMP and cGMP are derived from

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

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Cell Signalling and Transduction
In terms of cell communication, what do bacterial pathogens such as cholera and anthrax have in common?

They alter the chemical structure of key signaling molecules
They block the normal functioning of signal transduction mechanisms
They destroy the receptors for key signaling molecules
They prevent the production of key signaling molecules

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

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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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