Cell Signalling and Transduction
The signaling molecules called steroid hormones

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

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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 prevent the production of key signaling molecules
They destroy the receptors for key signaling molecules

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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
All of these
involves the activation of a G protein
must begin with receipt of the signal molecule by a surface receptor

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Cell Signalling and Transduction
Cell signaling can be classified into

three distinct types based on the signaling molecules
three distinct types based on the distance over which the signaling molecules act
two distinct types based on the distance over which the signaling molecules act
None of these

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Cell Signalling and Transduction
In the signal transduction mechanism known as protein phosphorylation

the signaling molecule binds to a surface receptor
receptor kinases play a key role in triggering the signal cascade
phosphorylated proteins act with enzymes to trigger the signal cascade
All of these

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