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

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

6. Biochemical anatomy of
Mitochondria [Lehninger]

7. When they get “burned” or oxidized, CO2 is released.
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

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

10. 14_07_Mito_catalyze.jpg Chemiosmotic theory (Paul Mitchell, 1960’s):
Coupling of electron transfer, proton pumping and ATP synthesis
14_07_Mito_catalyze.jpg
14_07_Mito_catalyze.jpg

11. 14_05_generate_energy.jpg Chemiosmotic process

12. 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.

13. 14_08_Uncoupl_agents.jpg Uncouplers (e.g. DNP),
are H+ carriers and makes
membrane permeable to H+
14_08_Uncoupl_agents.jpg

14. Chemiosmotic coupling: Experimental evidence

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

16. Lehninger Principles of Biochemistry

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

18. 14_13_electroch_gradie.jpg Oxidative phosphorylation [Fig. 14-13]

19. 14_21_Redox_potential .jpg
Electrons flow from –ve to +ve redox potential carriers
14_21_Redox_potential .jpg
14_21_Redox_potential .jpg

20. Lehninger Principles of Biochemistry

21. Lehninger Principles of Biochemistry

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

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

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

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

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

27. Transport across inner mitochondrial membrane
14_16_coupled_transpor.jpg
14_16_coupled_transpor.jpg

28. 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

29. Plastids are specialized for different functions.
Chloroplasts are green plastids specialized for photosynthesis.
Chromoplasts are 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.

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

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

32. 14_31_mito_chloroplas.jpg Mitochondria vs. Chloroplasts

33. 14_32_photsyn_react.jpg Light and dark reactions
of photosynthesis occur
in chloroplasts
14_32_photsyn_react.jpg
14_32_photsyn_react.jpg

34. 14_33_Chlorophyll.jpg
Chlorophyll molecule
14_33_Chlorophyll.jpg

35. 14_34_photosystem.jpg A photosystem = a reaction center + an antenna

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

37. Proton and electron circuits
In thylakoids [Lehninger]

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

39. 14_39_Carb_fix_cycle.jpg 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
14_39_Carb_fix_cycle.jpg

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

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

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