Which is the correct order of activation during phototransduction?

Study for the NBEO Ocular Physiology Exam. Utilize flashcards and multiple-choice questions to enhance your learning. Prepare effectively for your certification!

In phototransduction, which is the process by which light is converted into electrical signals in the retina, a specific sequence of molecular events is crucial for proper signaling. In the correct order of activation, all-trans-retinal is first produced from the isomerization of 11-cis-retinal upon photon absorption by rhodopsin, leading to the formation of metarhodopsin II.

After the formation of metarhodopsin II, this activated form of rhodopsin interacts with transducin, a G-protein, which is then activated. Upon activation, transducin subsequently activates phosphodiesterase 6 (PDE 6), an enzyme that hydrolyzes cyclic GMP (cGMP). The decrease in cGMP levels ultimately leads to the closure of cGMP-gated ion channels in the photoreceptor cell membrane, generating a hyperpolarizing signal that is transmitted to the bipolar cells.

Understanding the correct sequence in this pathway is essential for grasping how photoreceptors convert light into a biochemical signal. Therefore, the order beginning with all-trans-retinal, followed by metarhodopsin II, then transducin, and concluding with PDE 6 showcases the logical flow of

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