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
In terms of cell communication, what do bacterial pathogens such as cholera and anthrax have in common?

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

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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; G proteins
signaling molecule; target cell; receptors

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Cell Signalling and Transduction
The binding of ligands to many G-proteins linked receptors leads to shortlived

increase in the concentration of certain extracellular signaling molecules called first messenger
decrease in the concentration of certain intracellular signaling molecules called second messenger
decrease in the concentration of certain extracellular signaling molecules called first messenger
increase in the concentration of certain intracellular signaling molecules called second messenger

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