Biology 1002B Lecture Notes - Lecture 4: Channelrhodopsin, Photoreceptor Protein, Opsin

• School: Western University
• Department: Biology
• Course: Biology 1002B
• Professor: Tom Haffie

Document Summary

Lesson 4 light as energy and information. If light (cid:449)as a(cid:271)le to al(cid:449)a(cid:455)s hit (cid:272)ha(cid:374)(cid:374)elrhodopsi(cid:374) it (cid:449)ould(cid:374)"t k(cid:374)o(cid:449) (cid:449)here it is (cid:272)o(cid:373)i(cid:374)g from. In the (cid:272)hloroplast (cid:271)ut does(cid:374)"t ha(cid:448)e a(cid:374)(cid:455)thi(cid:374)g to do (cid:449)ith photos(cid:455)(cid:374)thesis. Light-gated ion channel (opened and closed due to the presence of light). More positive charged on the outside than the inside. Depolarizes the membrane when positively charged ions go through channelrhodopsin: causes an action potential that runs along the plasma membrane from the eyespot to the flagella, flagella moves based on the signals from the eyespot. Photoreceptor protein component called opsin (7 transmembrane domains): binds a pigment called retinal, therefore, retinal + opsin = channelrhodopsin. Proteins cannot absorb light, there must be a pigment attached in order to do so: opsin cannot absorb light, so it binds to retinal which is a pigment. For light to be used for information and energy: It has to be absorbed: pigment must be attached to a protein.