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BIOL 200 (Section 921) Lecture # 8 (Unit 6) June 28, 2006

BIOL 200 (Section 921) Lecture # 8 (Unit 6) June 28, 2006. UNIT 6: MITOCHONDRIA AND CHLOROPLASTS Reading : ECB 2nd ed. Chap 14 , pp. 453-492 and related questions, especially 14-3; 14-11B,C,E, H;14-13; 14-16.

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BIOL 200 (Section 921) Lecture # 8 (Unit 6) June 28, 2006

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  1. BIOL 200 (Section 921)Lecture # 8 (Unit 6)June 28, 2006 UNIT 6: MITOCHONDRIA AND CHLOROPLASTS Reading: • ECB 2nd ed. Chap 14, pp. 453-492 and related questions, especially 14-3; 14-11B,C,E, H;14-13; 14-16. • ECB 1st ed. Chap 13, pp. 407-442 and related questions, especially 13-3; 13-11B,C,E, H;13-13; 13-17.

  2. Learning objectives • Application of chemiosmotic theory to understand the structure-function relationships of the mitochondrial energy transduction system. • Understand the role of electron transport complexes in the establishment of mitochondrial proton gradient

  3. Unit 6: Mitochondria and chloroplasts [Chapter 14] 1 2 3 4 Fig. 14-3

  4. Fig. 14-3: Mitochondrial structures that you should know matrix Inner membrane(cristae) Outer membrane Intermembrane space

  5. Mitochondrial diversity [Fig. 14-2] 14_02_Mitochon_ATP.jpg

  6. Biochemical anatomy of Mitochondria [Lehninger]

  7. Fig. 13-2: reduced carbon compounds are the fuel for the mitochondria Food in Glycolysis in cytoplasm Citric acid cycle in matrix of mitochondrion When they get “burned” or oxidized, CO2 is released. Oxidative phosphor-ylation

  8. NADH kickstarts electron transport chain in mitochondria 14_04_NADH_electron.jpg

  9. Chemiosmotic theory (Paul Mitchell, 1960’s): Coupling of electron transfer, proton pumping and ATP synthesis 14_07_Mito_catalyze.jpg

  10. 14_05_generate_energy.jpg Chemiosmotic process

  11. Fig. 14-1: Mitchell’s chemiosmotic hypothesis 1. Electron transport causes protons to be exported to the inter-membrane space. 2. Proton gradient is harnessed by ATP synthase to make ATP.

  12. 14_08_Uncoupl_agents.jpg Uncouplers (e.g. DNP), are H+ carriers and makes membrane permeable to H+

  13. Chemiosmotic coupling: Experimental evidence

  14. Electron transport and H+ pumping in mitochondria 14_10_resp_enzy_comp.jpg

  15. Lehninger Principles of Biochemistry

  16. Electrochemical gradient (ΔμH+) = ΔV or ΔE + ΔpH 14_12_deltaV_deltapH.jpg

  17. Oxidative phosphorylation [Fig. 14-13] 14_13_electroch_gradie.jpg

  18. Electrons flow from –ve to +ve redox potential carriers 14_21_Redox_potential .jpg

  19. Lehninger Principles of Biochemistry

  20. Lehninger Principles of Biochemistry

  21. Cytochrome oxidase: e- transport, O2 reduction and H+ pumping 14_24_Cytochrome_ox.jpg O2 O2-  OH.  H2O2 Superoxide Hydroxyl free radical free radical

  22. FO-F1 ATP synthase complex: Uses proton electrochemical gradient to make ATP [Fig. 14-14]

  23. ATP synthase/ ATPase: a reversible enzyme [Fig. 14-15] 14_15_ATPsynthase2.jpg

  24. ATP synthase/ATPase: World’s smallest rotary motor: Experimental evidence

  25. Video pictures of rotation of the γ-subunit of ATP synthase

  26. Transport across inner mitochondrial membrane 14_16_coupled_transpor.jpg

  27. Learning objectives • Application of chemiosmotic theory to understand the structure-function relationships of the chloroplast energy transduction system. • Understand the role of electron transport complexes in the establishment of chloroplast proton gradient

  28. Plastids are specialized for different functions. • Chloroplastsare green plastids specialized for photosynthesis. • Chromoplastsare plastids filled with orange or yellow pigments that give colour to flowers and fruit. • Amyloplasts are plastids that store starch in storage tissues such as seeds, roots and stems. Amyloplasts in the root cap fall to one side of a cell and signal gravity perception • Etioplasts are plastids which develop in tissues in the dark and lack pigments. • Proplastids are a juvenile form of plastid that occurs in embryos and apical meristems. They give rise to all other types of plastids depending on requirements of each differentiated plant cell.

  29. Photosynthesis occurs in chloroplasts [Fig. 14-29]

  30. Three membranes in chloroplast: the outer, the inner and thylakoid membranes 14_30_3rd_compartmnt.jpg

  31. Mitochondria vs. Chloroplasts 14_31_mito_chloroplas.jpg

  32. Light and dark reactions of photosynthesis occur in chloroplasts 14_32_photsyn_react.jpg

  33. 14_33_Chlorophyll.jpg Chlorophyll molecule

  34. A photosystem = a reaction center + an antenna 14_34_photosystem.jpg

  35. Electron transport and H+ pumping in chloroplast 14_36_thylakoid_memb.jpg

  36. Proton and electron circuits In thylakoids [Lehninger]

  37. Photophosphorylation and NADP reduction [Fig. 14-37]

  38. 1. Carboxylation The carbon fixation cycle or Calvin cycle • Rubisco enzyme • 40% of total leaf soluble protein • Conc. In stroma: 4 mM 14_39_Carb_fix_cycle.jpg 3. Regeneration 2. Reduction

  39. Fig. 1-21: origin of chloroplasts. Early eukaryotic cell capable of photosynthesis Early eukaryote chloroplasts cyanobacterium

  40. Fig. 13-39: Phylogenetic tree based on rDNA sequences (Fig. 9-15, new book)

  41. What organisms are mitochondrial or chloroplast genes most closely related to? Mitochondrial genes are shown in red. chloroplasts genes are shown in green.

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