Final answer:
Color blindness is typically caused by abnormalities or a lack of opsins, a type of photoreceptor protein found in retinal cone cells responsible for color vision.
Step-by-step explanation:
Color blindness results from abnormalities in or lack of opsins, which are a type of photoreceptor protein found in cone cells of the retina. These proteins are vital for color perception as they are sensitive to different wavelengths of light corresponding to different colors. There are three kinds of cone cells, each with a different opsin that is tuned to specific wavelengths for the perception of red, green, and blue. The cones are concentrated in the fovea, the central region of the retina, and are responsible for central vision and color. The rods, on the other hand, contain a different pigment called rhodopsin and are more abundant in the peripheral regions of the retina, contributing to dim light and peripheral vision. When opsins are abnormal or missing due to genetic mutations or other factors, it can lead to various forms of color blindness, with red-green color deficiency being the most common.