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Chapter 6 Mitochondria and ChloroplastsFigure 14-37 Molecular Biology of the Cell(Garland Science 2008)Learning ObjectivesMitochondria and oxidative phosphorylationChloroplasts and PhotosynthesisMitochondria and Chloroplasts are semiautonomous organelles1.1 Mitochondrial plasticityRapid changes of shape are observed when an individual mitochondrion is followed in a living cell.Fusing with one another and then separating again in a living cell.The size and number of mitochondria reflect the energy requirements of the cell.Mitochondrial plasticityContains channel-forming protein,called Porin.Permeable to all molecules of 5 000 daltons or less.Outer membraneA mitochondrion contains two membrane-bounded compartmentsContains proteins with three types of functions:(1)Electron-transport chain:Carry out oxidation reactions;(2)ATP synthase:Makes ATP in the matrix;(3)Transport proteins:Allow the passage of metabolites Inner membrane(Impermeability)Intermembrane space and matrix Intermembrane space:Contains several enzymes use ATP to phosphorylate other nucleotides.Matrix:Enzymes;Mit DNA,Ribosomes,etc.How to study specific functions localized within the Mit Localization of metabolic functions within the mitochondrionOuter membrane:Phospholipid synthesisfatty acid desaturationFatty acid elongationMark:monoamine oxidaseInner membrane:Electron transportOxidative phosphorylationMetabolite transportCardiolipin/TPL(20%)Mark:cytochrome oxidaseIntermembrane spaceNucleotide phosphorylationMark:adenylate kinaseMatrixPyruvate oxidationTCA cycle oxidation of fatsDNA replication,RNA transcription,Protein translationMark:MDH(苹果酸脱氢酶苹果酸脱氢酶)1.2.Molecular basis of oxidative phosphorylation1.2.Molecular basis of oxidative phosphorylation最初电子供体最初电子供体最终电子受体最终电子受体1.2.1 Electron transport complexElectron transport chain5 种电子载体：黄素蛋黄素蛋白、细白、细 胞色素、泛醌、胞色素、泛醌、铁硫蛋白和铜原子铁硫蛋白和铜原子呼吸链电子载体按氧化按氧化还原电位从低向高排序还原电位从低向高排序As electrons move through the electron-transport chain,H+are pumped out across the inner membrane,and form Proton motive force;Electrons move through the inner membrane via a series of carriers of decreasing redox potentialProton motive force1.2.2 The structure of the ATP synthaseF1 particle is the catalytic subunit;F0 particle attaches to F1 and is embedded in the inner membrane.F1:5 subunits in the ratio 3:3:1:1:1 F F0:0:1a1a：2b2b：10-10-12c12c F1 particles have ATP synthase activity转子（转子（rotorrotor）：，旋转以调节3个催化位点的开放与关闭定子（定子（statorstator）：a、b2F1的共同组成Rotor and statorRotor and statorBoyer proposed in 1979,and was greatly stimulated by the publication in 1994 of the structure for F1 complex(X-ray)from bovine heart mitochondriaProton translocation through F0 drives ATP synthesis by F1:1.2.3 Binding change model and rotational catalysis Experimental demonstration of rotation of Fo and Japan researcher,Nature 386:300,1997.Experimental demonstration of rotation of Fo and From Yoh Wada et al Biochem.Biophys.Acta 1459:503,2000The ATP synthase is a reversible coupling device 1.2.4 Other roles for the proton-motive force in addition to ATP synthaseATP synthesis Active membrane transportRotation of bacterial flagella by proton-motive forceRegulate for Ca2+1.2.5 Mithchells chemiosmotic model(1961)A testable prediction followed from Mitchells hypothesisIf not all the detergent is removed,what will happen?Summary of the major activities during aerobic respiration in a mitochondrionNADHO2:3ATP/2e;FADH2 O2:2ATP/2e2.1.Chloroplasts resemble mitochondria but have an extra compartment2.2.Photosynthesis原初电子供体原初电子供体最终电子受体最终电子受体 The antenna complex and photochemical reaction center in a photosystemElectron transport in the thylakoid membrane and noncyclic photophosphorylation:Light-dependent reaction只有只有ATP的产的产生，没有生，没有NADPH和和O2Cyclic photophosphorylation Changes in redox potential during photosynthesisCalvin cycleCarbon dioxide fixation and the synthesis of carbohydrate in C3 plants CAM plants:CO2被被2次固定，但只次固定，但只需需1种细胞（种细胞（Mesophyll cell）The structure and function in C4 plants3.Organelle DNA vThe size range of organelle DNA is similar to that of viral DNAs.Mit DNA:from 300000bp(some land plants).DNA of Mit genome(in mammals)16500bp(0.001%of nuclear genome);Chl genomes are about 10 times larger and contain about 120 genes.Chl DNA:from 70000 to 200000bp(genome of land plants);vGenes in mtDNA encode rRNAs,tRNAs,and some mitochondrial proteinsHuman mt DNA:16,569bp 2 rRNAs（16s and 12s RNA）,22 tRNAs,13 polypeptides:NADH reductase.7 sub.Cty b-c1 complex.1 cytb Cyt oxidase.3 subunits ATP synthase:2 F0 sub Products of mt genes are not exported The organization of the liverwort(地钱地钱)Chl genomeMit and Chl are organelles semiautonomous.The synthesis of mt proteins is coordinatedMit and Chl have their own genetic systems
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