Cell Signalling and Transduction
Why is it that inhaling nitric oxide reduces blood pressure only in the lung tissue and not elsewhere in the body*?

Because nitric oxide breaks down quickly and thus cannot travel far
Because nitric oxide cannot cross cell membranes and enter the blood
Because other body tissues use a different signaling molecule
None of these

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Cell Signalling and Transduction
The signaling molecules called steroid hormones

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
bind to cell surface receptors to trigger chemical cascades

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

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

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