线绿体和叶绿体.ppt

EnergyGenerationinMitochondriaandChloroplasts Chapter7 1 Mitochondria inalleukaryoticcellsTherelationshipbetweenthestructureandfunctionofmit 2 Chloroplasts inplantcellsTherelationshipbetweenthestructureandfunctionofchl Mit Oxidativephosphorylation ATPChl Photosynthesis ATP NADPH Sugar A Mitochondrialstructureandfunction Thesizeandnumberofmitochondriareflecttheenergyrequirementsofthecell 1 Mitochondriaandoxidativephosphorylation Figure7 4Relationshipbetweenmitochondriaandmicrotubules Figure7 3Mitochondrialplasticity Rapidchangesofshapeareobservedwhenamitochondrionisvisualizedinalivingcell Figure7 5LocalizationofmitochondrianearsitesofhighATPutilizationincardiacmuscleandaspermtail Innerandoutermitochondrialmembranesenclosetwospaces thematrixandintermembranespace Outermembrane Containschannel formingprotein calledPorin Permeabletoallmoleculesof5000daltonsorless Innermembrane Impermeability Containsproteinswiththreetypesoffunctions 1 Electron transportchain Carryoutoxidationreactions 2 ATPsynthase MakesATPinthematrix 3 Transportproteins Allowthepassageofmetabolites Intermembranespace ContainsseveralenzymesuseATPtophosphorylateothernucleotides Matrix Enzymes MitDNA Ribosomes etc Figure14 6Fractionationofpurifiedmitochondriaintoseparatecomponents Thesetechniqueshavemadeitpossibletostudythedifferentproteinsineachmitochondrialcompartment Themethodshown whichallowstheprocessingoflargenumbersofmitochondriaatthesametime takesadvantageofthefactthatinmediaoflowosmoticstrengthwaterflowsintomitochondriaandgreatlyexpandsthematrixspace yellow Whilethecristaeoftheinnermembraneallowittounfoldtoaccommodatetheexpansion theoutermembranewhichhasnofoldstobeginwithbreaks releasingastructurecomposedofonlytheinnermembraneandthematrix B SpecificfunctionslocalizedwithintheMitbydisruptionoftheorganelleandfractionation Localizationofmetabolicfunctionswithinthemitochondrion Outermembrane Phospholipidsynthesis fattyaciddesaturation Fattyacidelongation Innermembrane Electrontransport Oxidativephosphorylation Metabolitetransport Intermembranespace Nucleotidephosphorylation Matrix Pyruvateoxidation TCAcycle oxidationoffats DNAreplication RNAtranscription Proteintranslation 2 Molecularbasisofoxidativephosphorylation A Molecularbasisofoxidation Electron transportchain B Molecularbasisofphosphorylation ATPsynthase ThestructureoftheATPsynthase F1particleisthecatalyticsubunit TheF0particleattachestoF1andisembeddedintheinnermembrane F1 5subunitsintheratio3 3 1 1 1 F0 1a 2b 12c F1particleshaveATPsynthaseactivity ProtontranslocationthroughF0drivesATPsynthesisbyF1 BindingChangeModelandrotationalcatalysis Boyerproposedin1979 andwasgreatlystimulatedbythepublicationin1994ofthestructureforF1complex X ray frombovineheartmitochondria Directexperimentalevidencesupportingtherotationalcatalysis Japanresearcher Nature386 300 1997 TheATPsynthaseisareversiblecouplingdevice Otherrolesfortheproton motiveforceinadditiontoATPsynthase C Mithchell sChemiosmotictheory 1961 ThepHandelectricalgradientresultingfromtransportofprotonslinksoxidationtophosphorylation Whenelectronsarepassedtocarriersonlyabletoacceptelectrons theH istranslocatedacrosstheinnermembrane Morethan2 1026molecules 160kg ofATPperdayinourbodies ElectronspassfromNADHorFADH2toO2 theterminalelectronacceptor throughachainofcarriersintheinnermembrane FMN Fe Scenter HemegroupFe CoQ Aselectronsmovethroughtheelectron transportchain H arepumpedoutacrosstheinnermembrane andformProtonmotiveforce Electronsmovethroughtheinnermembraneviaaseriesofcarriersofdecreasingredoxpotential Ifnotallthedetergentisremoved whatwillhappen Figure7 26AnexperimentdemonstratingthattheATPsynthaseisdrivenbyprotonflow Bycombiningalight drivenbacterialprotonpump bacteriorhodopsin anATPsynthasepurifiedfromoxheartmitochondria andphospholipids vesicleswereproducedthatsynthesizedATPinresponsetolight Summaryofthemajoractivitiesduringaerobicrespirationinamitochondrion NADH O2 3ATP 2e FADH2 O2 2ATP 2e 生物氧化产生ATP的统计一个葡萄糖分子经过细胞呼吸全过程产生多少ATP 糖酵解 底物水平磷酸化产生4ATP 细胞质 己糖分子活化消耗2ATP 细胞质 产生2NADH 经电子传递产生4或6ATP 线粒体 净积累6或8ATP丙酮酸氧化脱羧 产生2NADH 线粒体 生成6ATP三羧酸循环 底物水平的磷酸化产生 线粒体 2ATP 产生6NADH 线粒体 生成18ATP 产生2FADH2 线粒体 生成4ATP总计生成36或38ATP 3 Chloroplastandphotosynthesis A Comparisonofamitochondrionandachloroplast Figure14 39Thechloroplast Thisphotosyntheticorganellecontainsthreedistinctmembranes theoutermembrane theinnermembrane andthethylakoidmembrane thatdefinethreeseparateinternalcompartments theintermembranespace thestroma andthethylakoidspace Thethylakoidmembranecontainsalloftheenergy generatingsystemsofthechloroplast Inelectronmicrographsthismembraneappearstobebrokenupintoseparateunitsthatencloseindividualflattenedvesicles seeFigure14 40 buttheseareprobablyjoinedintoasingle highlyfoldedmembraneineachchloroplast Asindicated theindividualthylakoidsareinterconnected andtheytendtostacktoformaggregatescalledgrana A Awheatleafcellinwhichathinrimofcytoplasmcontainingchloroplastssurroundsalargevacuole B Athinsectionofasinglechloroplast showingthestarchgranulesandlipiddropletsthathaveaccumulatedinthestromaasaresultofthebiosynthesesoccurringthere C Ahigh magnificationviewofagranum showingitsstackedthylakoidmembrane CourtesyofK Plaskitt Figure7 42Photosynthesisinachloroplast Waterisoxidizedandoxygenisreleasedinthephotosyntheticelectron transferreactions whilecarbondioxideisassimilated fixed toproducecarbohydrateinthecarbon fixationreactions B Photosynthesis C Theantennacomplexandphotochemicalreactioncenterinaphotosystem Light dependentreaction Electrontransportinthethylakoidmembraneandnoncyclicphotophosphorylation Cyclicphotophosphorylation Changesinredoxpotentialduringphotosynthesis CarbondioxidefixationandthesynthesisofcarbohydrateinC3plants Calvincycle Figure14 43Theinitialreactionincarbonfixation Thisreaction inwhichcarbondioxideisconvertedintoorganiccarbon iscatalyzedinthechloroplaststromabytheabundantenzymeribulosebisphosphatecarboxylase Theproduct 3 phosphoglycerate isalsoanimportantintermediateinglycolysis thetwocarbonatomsshadedinblueareusedtoproducephosphoglycolatewhentheenzymeaddsoxygeninsteadofCO2 ThestructureandfunctioninC4plants 4 OrganelleDNAandproteinimporting A OrganelleDNA ThesizerangeoforganelleDNAissimilartothatofviralDNAs MitDNA from300 000bp somelandplants DNAofMitgenome inmammals 16 500bp 0 001 ofnucleargenome Chlgenomesareabout10timeslargerandcontainabout120genes ChlDNA from70 000 to200 000bp genomeoflandplants GenesinmtDNAencoderRNAs tRNAs andsomemitochondrialproteinsHumanmtDNA 16 569bp2rRNAs 22tRNAs 13polypeptides NADHreductase 7sub Ctyb c1complex 1cytbCytoxidase 3subunitsATPsynthase 2F0sub Productsofmtgenesarenotexported Theorganizationoftheliverwort 地钱 Chlgenome B MitandChlhavetheirowngeneticsystems MitandChlareorganellessemiautocephaly Thesynthesisofmtproteinsiscoordinated C ThetransportproteinintoMit AndChl TreeproteinstranslocatorsinMitmembranes TOM TIM andOXAcomplexaremultimericmembraneprotein thatcatalyzeproteintransportacrossMitmembrane TOM TIMstandfortranslocaseoftheouterandinnerMitmembranesrespectively TOMfunctionsacrosstheoutermembrane TIM TIM23andTIM22 functionacrosstheinnermembrane OXAmediatestheinsertionofinnermembraneproteinsthataresynthesizedwithintheMit OXAalsohelpsTOMandTIMtoinsertsomeproteinsintothematrix Translocationofprecursorstothematrixoccursatthesiteswheretheouterandinnermembranesareclosetogether TheproteinimportbyMit N terminalsignalsequenceisrecognizedbyreceptorsofTOM TheproteinistranslocatedacrossbothMitmembranesatornearspecialcontactsites OnlyunfoldedproteinscanbeimportedintoMit Mitprecursorproteinsremainunfoldedthroughinteractionswithhsp70chapero