Cell Signalling and Transduction
The enzyme that catalyzes the splitting of PIP2 into two molecules of inositol triphosphate (IP3) and diacylglycerol in cell signaling, is

phosphokinase C
lipokinase
phosphodiesterase C
phospholipase C

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Cell Signalling and Transduction
A signal cascade induced by adrenaline or thyroxine

All of these
must begin with receipt of the signal molecule by a surface receptor
involves the activation of a G protein
results in the activation of a sequence of enzymes needed for the cell effect

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

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Cell Signalling and Transduction
The signaling molecules called steroid hormones

are made in one location of the body but have their effects some distance away
are hydrophilic and so cannot penetrate the plasma membrane
bind to cell surface receptors to trigger chemical cascades
never enter the blood of humans

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