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.

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

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

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

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

Biochemical anatomy of Mitochondria [Lehninger]

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

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

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

14_05_generate_energy.jpg Chemiosmotic process

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.

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

Chemiosmotic coupling: Experimental evidence

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

Lehninger Principles of Biochemistry

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

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

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

Lehninger Principles of Biochemistry

Lehninger Principles of Biochemistry

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

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

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

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

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

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

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

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.

Photosynthesis occurs in chloroplasts [Fig. 14-29]

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

14_31_mito_chloroplas.jpg Mitochondria vs. Chloroplasts

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

14_33_Chlorophyll.jpg Chlorophyll molecule 14_33_Chlorophyll.jpg

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

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

Proton and electron circuits In thylakoids [Lehninger]

Photophosphorylation and NADP reduction [Fig. 14-37]

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

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

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

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