Also known as visual purple, a widely distributed
pigment concerned with light sensitivity.
Rhodopsin consists of a protein called opsin with a prosthetic
group called retinal of which vitamin
A is an essential precursor. Rhodopsin occurs in the rod
cells of vertebrate retinas. It is chemically
changed by the light, the change being the basis of how rods work as light-sensitive
receptors. Rhodopsin increases in amount in the dark, raising the sensitivity
of rods to faint light (the dark adaptation).
| Credit: Department of Ophthalmology,
University of Utah