answers: chromophore
context: Photoisomerase A photoisomerase is a protein in the eye that is responsible for isomerizing photopigments. In order for the eye to function properly, a special chemical called a chromophore is bound to a protein known as an opsin. When a photon strikes the chromophore, it changes shape (isomerizes). It is this change in conformation that the protein detects and eventually leads to vision. Before the chromophore can be reused, it must be converted back to its original conformation. The photoisomerase is the protein responsible for this change. In the mammalian retina, they are believed to be confined to the retinal </s> across different cone types. The process of phototransduction occurs in the retina. The retina has many layers of various cell types. The best-known photoreceptor cells ("rods" and "cones") form the outermost layer. They are the photoreceptors responsible for sight. The middle layer contains bipolar cells, which collect neural signals from the rods and the cones and then transmit them to the innermost layer of the retina, where the neurons called retinal ganglion cells (RGCs), a small percentage of which are themselves photosensitive, organize the signals and send them to the brain. Activation of rods and cones is actually hyperpolarization; when </s> Photodarkening Photodarkening is an optical effect observed in the interaction of laser radiation with amorphous media (glasses) in optical fibers. Until now, such creation of color centers was reported only in glass fibers . Photodarkening limits the density of excitations in fiber lasers and amplifiers. The experimental results suggest that operating at a saturated regime helps to reduce photodarkening. One could expect the term photodarkening to refer to any process when any object becomes non-transparent (dark) due to illumination with light. Formally, the darkening of the photo-emulsion also could be considered as photodarkening. However, recent papers use this term meaning
question: structural feature that is responsible for absorbing visible light