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BIBC102.SU05

BIBC102.SU05. Lecture 10 August 22, 2005 PHOTOSYNTHESIS. MIDTERM. F (<60 pts) D (>60 pts) C (>72 pts) B (>86 pts) A (>102 pts). 50 60 70 80 90 100 %

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BIBC102.SU05

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  1. BIBC102.SU05 Lecture 10 August 22, 2005 PHOTOSYNTHESIS

  2. MIDTERM F (<60 pts) D (>60 pts) C (>72 pts) B (>86 pts) A(>102 pts) 50 60 70 80 90 100 % 60 72 86 96 108 120 points

  3. PHOTOSYNTHESIS LNC Chapter 19 Section 19.6

  4. LNC Fig. 19-36

  5. LNC Fig. 19-37

  6. LNC Fig. 19-38

  7. The Light Reactions Photophosphorylation

  8. LNC Fig. 19-39

  9. The Physics of Light Absorption: E = hn = hc/l h = Planck’s constant (6.626 x 10-34 J.sec) c = speed of light (2.998 x 108 m/sec in vacuum) l = wavelength (380 - 700 nm for visible region) 1 mole of photons (1 Einstein) with l = 700 nm has the energy of 171 kJ

  10. CHLOROPHYLL LNC 19-40a

  11. PHYCOERYTHROBILIN LNC 19-40b

  12. b-CAROTENE LNC 19-40c

  13. Nature 416, 807 - 808 (2002) Coprophagy: An unusual source of essential carotenoids J. J. NEGRO*, J. M. GRANDE*, J. L. TELLA*, J. GARRIDO†, D. HORNERO†, J. A. DONÁZAR*, J. A. SANCHEZ-ZAPATA‡, J. R. BENÍTEZ§ & M. BARCELL§ * Department of Applied Biology, Estación Biológica de Doñana, CSIC, Pabellón del Perú, Avda María Luisa, s/n 41013 Seville, Spain † Food Biotechnology Department, Instituto de la Grasa, CSIC, Avda Padre García Tejero 4, 41012 Seville, Spain ‡ Area de Ecología, Departamento de Biología Aplicada, Universidad Miguel Hernández, 03312 Alicante, Spain § Zoo de Jerez, Taxdirt s/n 11404 Jerez de la Frontera, Spain e-mail: negro@ebd.csic.es The rare Egyptian vulture (Neophron percnopterus) stands out among the Old World vultures (Family Accipitridae ) because of its brightly ornamented head, which is coloured yellow by carotenoid pigments, and its practice of feeding on faeces. Here we show that Egyptian vultures obtain these pigments from the excrement of ungulates. To our knowledge,

  14. LUTEIN (XANTHOPHYLL) LNC 19-40d

  15. LNC 19-41

  16. LNC 19-44

  17. Fate of a photon absorbed by a molecule: • 1. Internal conversion: kinetic energy; rotations and vibrations • 2. Fluorescence:a photon is re-emitted, but at longer l • 3. Exciton transfer: • resonance energy transfer from one molecule to • another nearby molecule • 4. Photooxidation: • the excited molecule actually loses an electron to form a • cationic free radical • the free radical becomes a strong oxidizing agent

  18. A light-harvesting complex with 7 chlorophyll a, 5 chlorophyll b and 2 lutein molecules (a monomer is shown) the functional unit of a LHC is a trimer LNC Fig. 19-42

  19. Exciton transfer Photo- oxidation LNC 19-45

  20. A trimeric photosystem I viewed from the thylakoid lumen perpendicular to the membrane LNC 19-51b

  21. Photosystem I (monomer) with antenna chlorophylls and carotenoids Reaction center LNC 19-51c

  22. LNC 19-49

  23. special acceptor chlorophyll phylloquinone iron-sulfur center pheophytin Ferredoxin ([Fe-S] plastoquinone mobile quinone Cyt b6f complex Plastocyanin (Cu) flavoprotein- ferredoxin NADP+ oxidoreductase

  24. redox center hydrophobic membrane anchor PHYLLOQUINONE = A1 (in previous Figure)

  25. Photosystem I From PHOTOSYSTEM II FX , FA , FB and ferredoxin are [Fe-S] proteins NADP+ LNC 19-51a

  26. From: A. Zouni et al. Nature 409, 739-743 (2001) Structure of Photosystem II of Synechococcus elongatus

  27. LNC 19-56

  28. LNC 19-49

  29. The cytochrome b6f complex LNC 19-54b

  30. The cytochrome b6f complex To reaction center of PS I LNC 19-54c

  31. LNC 19-57

  32. LNC 19-53

  33. LNC 19-52

  34. cyclic photophosphorylation No oxygen produced No NADP+ reduced ATP is synthesized

  35. bacteriorhodopsin LNC Fig. 19-59

  36. LNC Fig. 19-59b

  37. 2 H2O + 2 NADP+ O2 + 2 NADPH + 2H+ ½ O2 + 2 H+ + 2e- H2O E’o = + 0.816 volts NADP+ + H+ + 2e-  NADPH E’o = - 0.324 volts DG’o = - 2 x 96.5 kJ/Vmol x (-1.240volts) = + 239 kJ/mol i.e. we need 2 x 239 kJ to make 2 moles of NADPH One mole of photons has ~180 kJ/Einstein From 8 moles of photons we get ~ 1440 kJ We also pump protons to set up a protonmotive force that can be used to make ATP From measurements: we make ~ 3 moles ATP per mole of O2 produced

  38. End of lecture 10 Aug. 22, 2005

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