Biology 1202B Lecture Notes - Lecture 3: Chlamydomonas Reinhardtii, Motility, Visual Cortex
6 Apr 2018
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Light gets absorbed form retinal in rhodopsin and. 3 sends it to bipolar cells ganglion cells. Ganglion cells translates it to optic nerve fibre and this goes to the visual cortex: rods for night cons for day, rods have cells and they contain molecules called rhodopsin. Retinal absorbs light and changes shape and goes from cis-trans. When retinal leaves, then opsin also changes its shape. Protein called transducin (3 parts: alpha, beta, gamma) binds to opsin using gtp and initiates the phototransduction cascade. Once protein is bound, beta and gamma leave and alpha remains. Alpha then binds to phosphodiastarase to hydrolyze cyclic gmp and makes it non- cyclic. When cyclic gmp is bound to sodium channel, the channel is open. However, pde comes and changes it to non-cyclic pde then hydrolyzes cgmp reducing its concentration and closes na + channel. This sends an electrical signal to the brain.
