NROC64H3 Lecture 2: Lecture 2
Document Summary
Rhodopsin is a photopigment that is extremely sensitive to light and is what enables us to see in low- light conditions. It is made up of retinal (vitamin a) and opsin. When rhodopsin is hit by light, 11-cis retinal which is normally bent isomerizes into straight all trans retinal. For either the rod or the cone (which exist in the retina), light causes the photoreceptors to. They respond slowly with graded potentials and can respond to even a single photon. Phototransduction in rods: in the dark, the rods remain depolarized, when light hits the rhodopsin, after the isomerization, the g-protein known as transducin, gets a. Gtp that replaces its gdp: this gdp binds with phosphodiesterase to convert cgmp to gmp. Sodium channels are no longer gated by cgmp and thus they close causing hyperpolarization. Once the rods and cones hyperpolarize, the bipolar cells are the next stage of transmission.
