Which of the following is a step in photoreception in the rods?

Question

Quizplus · Accepted Answer

[II C 4]. Photoreception involves the following steps. Light converts 11-cis retinal to all-trans retinal, which is converted to such intermediates as metarhodopsin II. Metarhodopsin II activates a stimulatory G protein (transducin), which activates a phosphodiesterase. Phosphodiesterase breaks down cyclic guanosine monophosphate (cGMP), so intracellular cGMP levels decrease, causing closure of $\mathrm{Na}^{+}$channels in the photoreceptor cell membrane and hyperpolarization. Hyperpolarization of the photoreceptor cell membrane inhibits release of the neurotransmitter, glutamate. If the decreased release of glutamate interacts with ionotropic receptors on bipolar cells, there will be inhibition (decreased excitation). If the decreased release of glutamate interacts with metabotropic receptors on bipolar cells, there will be excitation (decreased inhibition).

Which of the Following Is a Step in Photoreception in the Rods