Which of the following statements are correct regarding phototransduction and olfactory transduction?

Question

Quizplus · Accepted Answer

Phototransduction and olfactory transduction share several common features in their signal transduction pathways:
a) Odorant molecules and light are both detected by G-protein coupled receptors (GPCRs). In the olfactory system, odorant molecules bind to GPCRs known as olfactory receptors located on the membrane of olfactory sensory neurons. In the visual system, light is detected by GPCRs called opsins, which are located in the photoreceptor cells of the retina.
b) Second messenger systems are used in both systems. In olfactory transduction, the binding of an odorant to its receptor activates a G-protein (specifically, G_olf), which then activates adenylyl cyclase to convert ATP to cyclic AMP (cAMP). In phototransduction, the activation of the opsin by light leads to a cascade that ultimately changes the levels of cyclic GMP (cGMP) within the photoreceptor cells.
c) Cyclic nucleotide-gated ion channels are used in both systems to control cell membrane voltage. In the olfactory neurons, cAMP opens cyclic nucleotide-gated ion channels, allowing positive ions to flow into the cell and depolarize the membrane, leading to an action potential. Similarly, in photoreceptor cells, cGMP binds to and opens cyclic nucleotide-gated ion channels, allowing the influx of positive ions. However, in the dark, these channels are open, and light leads to a reduction in cGMP levels, causing the channels to close and the cell to hyperpolarize.
Therefore, all of the statements (a, b, and c) are correct regarding phototransduction and olfactory transduction.

Which of the Following Statements Are Correct Regarding Phototransduction and Olfactory