PSC 101 Lecture Notes - Lecture 8: Optic Disc, Photopsin, Visual Phototransduction
Document Summary
The phototransduction cascade: the phototransduction cascade (ptc) - makes the brain recognize that there is light entering the eyeball. The process of making the light neural impulse by turning off a rod. Normally on, but when light hits it, the rod turns off: ptc is set of steps that turn it off. Inside rod are a lot of optic disks stacked on top of one another: a lot of proteins on the disks. One is rhodopsin (on a cone the same protein is called a photopsin), a multimeric protein with 7 discs, which contains a small molecule called retinal (11-cis retinal). This begins the cascade: next, there"s a molecule called transducin made of 3 different parts alpha, beta, gamma that is attached to the rhodopsin typically. When the rhodopsin changes shape, transducin breaks from rhodopsin, and alpha subunit binds to another disk protein called phosphodiesterase (pde). Pde takes cgmp and converts it to regular gmp.
