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The Phototransduction Cascade 1. The Phototransduction Cascade (PTC) - makes the brain recognize that there is light entering the eyeball. The process of making the light à neural impulse by turning off a rod. The neural impulse can turn on other cells and eventually be processed by the brain. • Ret...

The Phototransduction Cascade 1. The Phototransduction Cascade (PTC) - makes the brain recognize that there is light entering the eyeball. The process of making the light à neural impulse by turning off a rod. The neural impulse can turn on other cells and eventually be processed by the brain. • Retina is made off a bunch of different cells – rods and cones. • As soon as light is presented to a rod, it takes light and converts it to a neural impulse. Normally on, but when light hits it, the rod turns off. • PTC is set of steps that turn it off. o Inside rod are a lot of optic disks stacked on top of one another. o 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). When light hit, comes through pupil and hit the retinal, then it rods, some of the light hits rhodopsin (which contains the retina) and causes the retinal to change conformation from bent to straight conformation (11-trans retinal). o When retinal changes shape, rhodopsin changes shape (closely linked molecules). This begins the cascade. o Next, there’s a molecule called transducin made of 3 different parts – alpha, beta, gamma that is attached to the rhodopsin typically. sunlight -submit prokin on 035733] our rhodopsin · L ↳ ↑ retinal Transducin zis 21 Yones j ↳ & When ransduction I hits sunlig 44 ] Photo lascade of f ↓ changes , causes rhodopsin % Lcome Opoz)] G brain when retinal which hits 3confirmation then to change 3 comp NJ ⑤ & ⑪Bipolaror Loo > center- on wight wight off becauses Not channels to close less which causes sodium in cell whicha