Abstract
Animal retinas possess photoreceptor cells specialized to receive photons and convert them into neural signals. There are two types of visual cells, called rods and cones. Rods function in dim light conditions, and their photosensitivity is sufficiently high to respond to a single photon. Cones show rapid photoresponse, and the combination of cones having different wavelength sensitivity enables color vision. The transduction cascade in visual cells is initiated by the activation of G protein by photoactivated visual pigment, and this eventually results in the hyperpolarization of the cell. Recent progress in the study of the molecular basis of vision is reviewed.
