[Campbell Biology P.1168] When a photon of light is absorbed by retinal within rhodopsin, wha... | Practice Question

When a photon of light is absorbed by retinal within rhodopsin, what is the immediate molecular change that occurs?

  • A: Retinal changes from its trans isomer to its cis isomer.
  • B: The opsin protein detaches completely from retinal, leading to its degradation.
  • C: Retinal undergoes a conformational change from an angled (cis) shape to a straight (trans) shape, activating opsin.
  • D: Rhodopsin splits into its constituent amino acids, releasing energy for vision.

Explanation

The text explicitly states: 'Absorption of light shifts one bond in retinal from a cis to a trans arrangement, converting the molecule from an angled shape to a straight shape. This change in configuration activates the opsin protein to which retinal is bound.'