Which vitamin serves as a component of rhodopsin and iodopsin?

Vitamin A is essential for the formation of the visual pigments rhodopsin and iodopsin, which are crucial for vision. Rhodopsin is found in the rod cells of the retina and is responsible for vision in low-light conditions, allowing us to detect light and dark. Iodopsin, on the other hand, is located in the cone cells and is responsible for color vision and function in bright light.

The structure of these pigments is based on retinal, which is derived from vitamin A. When light hits these pigments, it causes a conformational change in retinal, initiating a cascade of biochemical events that ultimately leads to the perception of light. This is a critical process in the visual cycle and underscores the vital role of vitamin A in maintaining healthy vision.

Other vitamins listed do not play a direct role in the formation or functionality of visual pigments like rhodopsin and iodopsin. Thus, the involvement of vitamin A in the structure and function of these compounds makes it the correct choice in this context.