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Unformatted text preview: 4/4/12 1 Transduction • Pigments: Light-absorbing molecules • Located in outer segments of photoreceptors Disks are discarded and replaced Photoreceptor pigments located on disks Transduction • Retinal (Vitamin A) + Opsin = Rhodopsin – The rod photopigment Light makes the retinal change shape Transduction This change is called “ bleaching ” of photopigment: Can’t activate unless in “unbleached” state Takes time to get back to active state Dark adaptation: increase in sensitivity as photopigment “regenerates” * In the white areas of the slide you are bleaching your photopigments Now, even though uniform luminance, the bleached receptors are not as active so those areas appear darker than unbleached (previous dark) areas of your retina. G-protein cascade of events closes a Na + channel that is normally open in the dark http://webvision.med.utah.edu/movies/trasduc.mov 4/4/12 2 Transduction • Light changes shape of pigment • G-protein activated • Change in enzyme activity...
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This note was uploaded on 04/09/2012 for the course EXP 3202 taught by Professor Staff during the Spring '12 term at Florida State College.
- Spring '12