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

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

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

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

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Cell Signalling and Transduction
Which of the following is true about a hydrophilic signaling molecule?

Its receptor is located in the cytosol of the target cell
Since it can enter the cell, it directly affects some specific cell process
It might trigger a signal cascade that causes some effect in a cell
It is a steroid

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