Human color vision depends on three types of cone cells in the retina. Although all three contain the same light-absorbing molecule, 11-cis-retinal, differences in the surrounding protein determine sensitivity to red, green, or blue light. Human color vision depends on three types of cone cells in the retina. Although all three contain the same light-absorbing molecule, 11-cis-retinal, differences in the surrounding protein determine sensitivity to red, green, or blue light. Understand... [3267 chars]