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

3. 50 60 70 80 90 100 % 60 72 86 96 108 120 points F ( 60 pts) C (>72 pts) B (>86 pts) A (>102 pts) MIDTERM

4. PHOTOSYNTHESIS LNC Chapter 19 Section 19.6

6. LNC Fig. 19-36

7. LNC Fig. 19-37

8. LNC Fig. 19-38

11. The Light Reactions Photophosphorylation

12. LNC Fig. 19-39

13. The Physics of Light Absorption : E = h = hc/ h = Planck’s constant (6.626 x 10 -34 J.sec) c = speed of light (2.998 x 10 8 m/sec in vacuum) = wavelength (380 - 700 nm for visible region) 1 mole of photons (1 Einstein) with = 700 nm has the energy of 171 kJ

14. CHLOROPHYLL LNC 19-40a

15. PHYCOERYTHROBILIN LNC 19-40b

16.  -CAROTENE LNC 19-40c

17. 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,

18. LUTEIN (XANTHOPHYLL) LNC 19-40d

19. LNC 19-41

20. LNC 19-44

21. 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  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

22. LNC Fig. 19-42 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

23. LNC 19-45 Exciton transfer Photo- oxidation

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

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

26. LNC 19-49

27. pheophytin plastoquinone mobile quinone Cyt b 6 f complex Plastocyanin (Cu) special acceptor chlorophyll phylloquinone iron-sulfur center Ferredoxin ([Fe-S] flavoprotein- ferredoxin NADP+ oxidoreductase

28. PHYLLOQUINONE = A 1 (in previous Figure) redox center hydrophobic membrane anchor

29. LNC 19-51a Photosystem I F X, F A, F B and ferredoxin are [Fe-S] proteins From PHOTOSYSTEM II NADP +

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

32. LNC 19-56

33. LNC 19-49

34. LNC 19-54b The cytochrome b 6 f complex

35. LNC 19-54c The cytochrome b 6 f complex To reaction center of PS I

36. LNC 19-57

37. LNC 19-53

38. LNC 19-52

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

41. bacteriorhodopsin LNC Fig. 19-59

42. LNC Fig. 19-59b

43. 2 H 2 O + 2 NADP +  O 2 + 2 NADPH + 2H + ½ O 2 + 2 H + + 2e -  H 2 OE’ o = + 0.816 volts NADP + + H + + 2e -  NADPHE’ o = - 0.324 volts  G’ 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 O 2 produced

44. End of lecture 10 Aug. 22, 2005