Retinal & Rhodopsin - wiki

Retinal is also known as retinaldehyde. It was originally called retinene, and renamed afterwards it was discovered to be vitamin A aldehyde. Retinal is one of the many forms of vitamin A (the number of which varies from species to species). Retinal is a polyene chromophore, bound to proteins called opsins, and is the chemical basis of animal vision. Retinal allows certain microorganisms to convert light into metabolic energy.

The 11-cis Retinal is an isomer of retinal. The 11-cis Retinal forms half of the rhodopsin (type of visual pigment) molecule (the other half of rhodopsin is composed of opsin) which is an essential endogenous chemical for the function of visual perception. The enzyme retinal isomerase catalyzes the conversion of Retinal to 11-cis Retinal.

Rhodopsin (also known as visual purple) is a light-sensitive receptor protein involved in visual phototransduction. It is named after ancient Greek ῥόδον (rhódon) for “rose”, due to its pinkish color, and ὄψις (ópsis) for “sight”. Rhodopsin is abiological pigment found in the rods of the retina and is a G-protein-coupled receptor (GPCR).

A photoreceptor cell is a specialized type of neuron found in the retina that is capable of phototransduction. The great biological importance of photoreceptors is that they convert light (visibleelectromagnetic radiation) into signals that can stimulate biological processes.

Visual perception is the ability to interpret the surrounding environment by processing information that is contained in visible light.