Cell Signalling and Transduction
When a __________ reaches its __________ , there is a specific means of receiving it and acting on the message. This task is the responsibility of specialized proteins called __________ .

signaling molecule; target cell; G proteins
signaling molecule; receptor; G proteins
kinase; receptor; proteases
signaling molecule; target cell; receptors

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Cell Signalling and Transduction
The signaling molecules called steroid hormones

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

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

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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
None of these
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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Cell Signalling and Transduction
A signal cascade induced by adrenaline or thyroxine

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

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