Class 2 PDF-3 - Denis Maxwell PDF

Title	Class 2 PDF-3 - Denis Maxwell
Author	Wesley Tran
Course	Biology for Science II
Institution	The University of Western Ontario
Pages	5
File Size	404.8 KB
File Type	PDF
Total Downloads	24
Total Views	131

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Summary

Denis Maxwell...

Description

Class 2: Light: a source of Energy & Information

Structure & function of the eyespot

Channelrhodopsin

Chloroplast membrane

1

Transduction of eyespot signal

Channelrhodopsin = retinal + opsin Photoreceptor

Absorbance

400

450

500

550

600

Wavelength (nm)

2

Light absorption of chlorophyll 400

Higher excited state

e-

600

Wavelength (nm)

500

Lower excited state

Absorbance

e700

Ground state

Photoisomerization of channelrhodopsin

Trans

Cis

3

Phototransduction of a rod cell (the eye) Plasma membrane

Photoreceptor disk Photoreceptor discs Plasma membrane Cytoplasmic space Cilium Mitochondria Golgi Endoplasmic reticulum Nucleus

Synaptic terminal

Phototransduction versus photosynthesis Photochemistry

e-

Rod/Cone cell Isomerization of retinal cis

trans

Photosystem Oxidation of chlorophyll Chl*

Chl+ + e-

4

Optogenetics • Express channelrhodopsin in brain neurons. • Stimulate them using blue light. • Map the brain.

Optogenetics: the steps Gene encoding Chlamydomonas opsin

5...