Cell Signalling and Transduction
A cell is known to respond to a particular signaling molecule. Which of the following must be true of this cell?

It is also the site of production for the signaling molecule
It is incapable of signal transduction
It is in the heart muscle
It contains the receptor for the signaling molecule

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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
involves the activation of a G protein
All of these
results in the activation of a sequence of enzymes needed for the cell effect

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

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

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Cell Signalling and Transduction
Self-phosphorylation is an excellent mechanism for triggering specific catalytic function of the proteins involved in signal cascades because it

allows hydrophilic signaling molecules to cross the plasma membrane
makes the receptor more likely to capture the signaling, molecule
None of these
changes the shape and thus the enzymatic activity of the proteins involved

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

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

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