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
are made in one location of the body but have their effects some distance away
never enter the blood of humans

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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
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
Which of the following is true about a hydrophilic signaling molecule?

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

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

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