Biology 1002B Lecture Notes - Lecture 4: Channelrhodopsin, Cell Membrane, Opsin
20 Feb 2017
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Carotenoid is found in b/w thylakoid (in chloroplast) (red dots on slide) Channelrhodopsins (imp. mol. ) sits on plasma membrane (not in chloroplast) (blue dots on slide) Only detects light from the front, can only hit channelrhodopsin (active mol. that leads to phototaxis) from front, otherwise it wouldn"t know where light was coming from. Channelrhodopsin light-gated (light opens gates) ion channel which allows ca and protein ions to come through. If light is present, gate opens, allowing ca ions into cell gate is not discriminatory (lets proteins and ions in) depolarizing membrane (diff. becomes less)depolarization causes action potentialinfo. from plasma membrane to flagella. More + charge outside than inside cell. Light has to be absorbed, pigment must be linked to a protein. Protein part is: opsin (7 transmembrane domains) Retinal that is in the protein (need opsin + retinal = channelrhodopsin) Retinal absorbs light, absorbs in blue and green. Need to know what chlorophyll and amino acids (in text)
