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

lipokinase
phospholipase C
phosphodiesterase C
phosphokinase C

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

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Cell Signalling and Transduction
Nitroglycerin has long been administered to human patients suffering from chronic chest pain (angina). This medication works because it

breaks down into nitric oxide, which increases blood flow to the heart
mimics the action of signal receptors
is broken down into hormones that affect the heart
interferes with chemical cascades that trigger contraction of heart muscle

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Cell Signalling and Transduction
Two key organizing principles for large multicellular organisms are

cell specialization and communication between cells
prokaryotic cell structure and cell specialization
communication between cells and simple nerve reflexes
simple nerve reflexes and cell specialization

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

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

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

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