photosynthesis: light reactions - wou homepageguralnl/gural/451photosynthesis.pdf ·...
TRANSCRIPT
![Page 1: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/1.jpg)
Photosynthesis: Light ReactionsCyanobacteria
• Overview• Structure of chloroplast• Absorption of Light• Photosystems• Electron transport
chain• Photophosphorylation• Electron flow water to
oxygen• Light energy
![Page 2: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/2.jpg)
Overview
• Located in the chloroplast • Converts light energy into chemical energy • requires pigments to absorb light energy
![Page 3: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/3.jpg)
Structure of chloroplast • Double membrane
organelle, 5-20 um size • Contains DNA, RNA,
ribosomes• Third membrane
system: Thylakoids• Five major protein
complexes on the thylakoid membranes
• Stroma• Thylakoid lumen • Stroma lamellae
![Page 4: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/4.jpg)
Absorption of Light • Pigments:• Chlorophyll: a, b and
bacteriochlorophylls• Carotenoids:
xanthophylls and β-carotene
• Absorption spectrum and action spectrum
• Assembled into complexes
![Page 5: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/5.jpg)
Pigments
![Page 6: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/6.jpg)
Absorption spectrum and action spectrum
![Page 7: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/7.jpg)
Fate of a photon of light absorbed
• Energy and wavelength relationship
• Different orbital levels • Heat • Fluorscencse• Phosphorescence and
the triplet state • Resonance energy
transfer • Photochemistry
![Page 8: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/8.jpg)
Electron orbitals
![Page 9: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/9.jpg)
Photosystems• Located in thylakoid
membranes, stacked and unstacked regions
• PS II-- P680
• PS I-- P700
• Reaction centers • Emerson Enhancement
effect and the far red drop-off
• Evidence for 2 photosystems
![Page 10: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/10.jpg)
Emerson Enhancement effect and the far red drop-off
Quantum yield = amt O2 produced / number of photons absorbedIf 1 all photons contribute to process.
![Page 11: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/11.jpg)
Electron transport chain
• Location and order • Transport of e- and protons between photosystems• Electron carriers • Production of NADPH
![Page 12: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/12.jpg)
Photosystem II
• Pair of chl a molecules in D1 and D2 sub-unit
• Pheophytin acceptor of electrons (2H+ instead of Mg)
• Transferred to plastoquinone
![Page 13: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/13.jpg)
Photosystem ICytochrome b6f complex
![Page 14: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/14.jpg)
Z scheme
![Page 15: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/15.jpg)
Orientation in thylakoid membrane
![Page 16: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/16.jpg)
Non-cyclic Photophosphorylation
![Page 17: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/17.jpg)
Cyclic Photophosphorylation
![Page 18: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/18.jpg)
Electron flow water to oxygen
• Oxygen evolving complex
• Mn dependent complex
• in thylakoid lumen • transitions with
flashes
![Page 19: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/19.jpg)
Oxygen evolution
![Page 20: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/20.jpg)
Photoinhibition and excess light energy
![Page 21: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/21.jpg)
Location of protein complexes
![Page 22: Photosynthesis: Light Reactions - WOU Homepageguralnl/gural/451Photosynthesis.pdf · Photosynthesis: Light Reactions Cyanobacteria • Overview • Structure of chloroplast • Absorption](https://reader031.vdocuments.us/reader031/viewer/2022021522/5b93dbf609d3f2130d8b9396/html5/thumbnails/22.jpg)
Herbicides
Diruron and atrazine: PS II inhibitiors, bindTo D1 sub-unit block formation of QH2.