Of the following, the earliest event in phototransduction is A) Exchange of GTP for GDP on the alpha subunit of transducin B) Activation of guanylate cyclase C) Activation of guanylate cyclase phosphodiesterase D) Closing the Na⁺ channel E) Conversion of 11 cis retinal to all trans retinal

Question

Quizplus · Accepted Answer

The earliest event in phototransduction is the conversion of 11-cis retinal to all-trans retinal. This occurs when light is absorbed by the photoreceptor cells in the retina, specifically by the photopigment rhodopsin, which contains the 11-cis retinal as its chromophore. This conversion triggers a cascade of biochemical events leading to the hyperpolarization of the photoreceptor cell and the initiation of the visual signal.

Of the Following, the Earliest Event in Phototransduction Is