Cell Signalling and Transduction
Which of the following statements about G proteins is false?

They bind to and are regulated by guanine nucleotides
They must be active before the cell can make needed cAMP
They are involved in signal cascades
They become activated when bound to GDP

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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 __________ .

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

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

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Cell Signalling and Transduction
The signaling molecules called steroid hormones

are hydrophilic and so cannot penetrate the plasma membrane
bind to cell surface receptors to trigger chemical cascades
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
cAMP and cGMP are derived from

GTP and ATP by the actions of adenylate cyclase and guanylate cyclase respectively
ATP and GTP by the actions of guanylate cyclase and adenylate cyclase respectively
None of these
ATP and GTP by the actions of adenylate cyclase and guanylate cyclase respectively

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