Image sharpness (slower but prettier)
The actual absorbing of light is performed by one magical molecule--retinal. As in hemoglobin, special functionality is provided by a non-protein factor which is bound by the protein (opsin). The details of structure and surface of the opsin molecule determine what wavelengths of light actually "excite" retinal. When light of the correct energy (= wavelength) strikes retinal, it undergoes a change in structure that triggers a series of events that culminate in a nerve signal.

In the initial view, the double bond that undergoes a change when its electrons are excited by light is shown as light blue

Pocket sidechains


Growing opsin

Thread in backbone

Entire protein Sidechains that contact retinal are dotted


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