When light strikes the rhodopsin in a rod, retinal isomerizes, initiating a signal transduction pathway that
A)depolarizes the neighboring bipolar cells and initiates an action potential in a ganglion cell.
B)depolarizes the rod, causing it to release the neurotransmitter glutamate, which excites bipolar cells.
C)hyperpolarizes the rod, reducing its release of glutamate, which excites some bipolar cells and inhibits others.
D)hyperpolarizes the rod, increasing its release of glutamate, which excites amacrine cells but inhibits horizontal cells.
E)converts cGMP to GMP, opening sodium channels and hyperpolarizing the membrane, causing the rhodopsin to become bleached.

Question

Quizplus · Accepted Answer

When light strikes the rhodopsin in a rod, retinal isomerizes, which activates an enzyme called transducin. Transducin then activates the enzyme phosphodiesterase, which breaks down cGMP, causing the ion channels to close and the rod cell to hyperpolarize. This reduction in the release of glutamate by the rod cell leads to the inhibition of some bipolar cells and excitation of others, resulting in the generation of action potentials in ganglion cells. Therefore, option C is the best answer.

When Light Strikes the Rhodopsin in a Rod, Retinal Isomerizes