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

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

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

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

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Cell Signalling and Transduction
The signaling molecules called steroid hormones

never enter the blood of humans
are hydrophilic and so cannot penetrate the plasma membrane
are made in one location of the body but have their effects some distance away
bind to cell surface receptors to trigger chemical cascades

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

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

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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 guanylate cyclase and adenylate cyclase respectively
ATP and GTP by the actions of adenylate cyclase and guanylate cyclase respectively

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