Lecture7 - Photosynthesis 6 CO2 + 12 H2O + light C6H12O6 +...

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1 Photosynthesis 6 CO 2 + 12 H 2 O + light C 6 H 12 O 6 + 6 H 2 O + 6 O 2 Requirements: light, pigments, access to CO 2 “Light reactions” Light capture pigments absorption and action spectra pigment activation Photophosphorylation chemiosmotic ATP synthesis cyclic photophosphorylation noncyclic photophosphorylation “Dark reactions” Chloroplasts are photosynthetic organelles •thylakoid membranes are site of light reactions •stroma is site of dark reactions Three processes of photosynthesis: In thylakoids: 1) light capture 2) pigment regeneration In stroma: 3) “dark reactions” Goal of light reactions: Produce ATP and NADPH to provide energy and reducing power for building sugars Mechanism: uses potential energy from H+ gradient produced by capture of light energy •Light = form of electromagnetic energy •Units of light energy = photons •Energy content is inversely proportional to wavelength •High energy = ionizing radiation •Visible light (380-750 nm) can raise electron to higher energy level
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2 Excitation of a molecule by absorption of a photon Electron in a higher energy orbital is more easily lost to an oxidizing agent Chloroplast pigments absorb red and blue light •Capture of light energy involves absorption of photons •Wavelengths not absorbed (reflected or transmitted) give the pigment its color Absorption vs. action spectra •Absorption spectra show which wavelengths absorbed by given molecule •Action spectra show which wavelengths effective for
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This note was uploaded on 04/07/2008 for the course MCDB 1B taught by Professor Weimbs during the Winter '08 term at UCSB.

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Lecture7 - Photosynthesis 6 CO2 + 12 H2O + light C6H12O6 +...

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