课件生物化学6-photosynthesis光合作用

Lecture （光合作用Zhang: :1ChloroPhotophosphorylation（光合磷酸化Photorespiration（光呼吸2IntroductiontoTurningsunlightintoreduced1molATP≈Ananabolic,endergonic,CO2requiringprocessthatuseslightenergyandH2Otoproduceorganicmacromolecules(glucose)4Start5 purplepurple

CO２+2H２O→(CH２O)+O2CO２+2H２S→(CH２O)+2S1931C.B.VanNiel：overallequationfor HistoryofDoestheincreaseinmassofa ntcomefromtheair?Thesoil?TheWater?EarlyresearchfocusedontheoverallLaterresearchersinvestigatedthedetailedchemical 7VanHelmont’sExperiment ntedaseedintoapremeasuredamountofsoilandwateredfor5yearsWeighednt&ntwas75kg,SoiltheConcludedmasscamefrom8Priestley’sExperimentBurnedcandleinbelljaruntilitwentcedsprigofmintinbelljarforafewCandlecouldberelitand ntsreleasedsubstance(O2)necessaryforburning.Ingenhousz’sExperimentShowedthatPriestley’sresultsonlyoccurredinthepresenceofLightwasnecessaryfornttoproducethe“burninggas”orRepeatedpriestlyexperimentwithandwithoutJuliusRobertMayerProposedthatntcanconvertlightenergyintochemicalenergySamuelRuben&MartinKamenUsedisotopestodeterminethattheoxygenliberatedinphotosynthesiscomesfromMelvinCalvinFirsttotracethepaththatCO2takesinformingglucoseDoesNOTrequireCalledtheCalvinCycleorlightindependentreactionAlsoknownasthedarkRudolphMarcus(1992StudiedthelightindependentreactionsFirsttodescribetheelectrontransportchainWheredoesphotosynthesis mesophyllChlorost（叶绿体Organellewherephotosynthesistakes类囊基质片基kk（类 stPigmeChlorophyllChlorophyllThelightreactionsofphotosynthesis---directlydependentontheabsorptionoflight,theresultingphotochemistrytakeselectronsfromH2Oanddrivesthemthroughaseriesofmembrane-boundcarriers,producingNADPHandATP.（lightdependentreaction）TheThecarbon-assimilationreactionsofreduceCO2withelectronsfromNADPHandenergyfromATP.（darkreaction，lightindependentreaction）Lightreactionsareassociatedwiththethylakoid（类囊体）Light-independentreactionsareassociatedwiththestroma（基质>200chlorophyllamoleculesLittlechlorophyllb （类胡萝卜素）pigmentwithApair specialchlorophylla PrimaryelectronacceptormoleculecalledPhotosystemChlorophyllaß-carotenepigmentsattachedtoproteinSmallamountofchlorophyllbApairofspecialchlorophyllacalledPrimaryelectronacceptormoleculecalledAModeloftheOrientationoftheMajorEnergyComplexesWithintheThylakoid蓝TheStuctureof醌褐藻天线蛋白（ 合体放氧initiatesanoxidation-reductionPSⅡ的WatersplittingcomplexTheStuctureof蓝叶绿素叶绿GeneratesreducedThroughNADP eitreducesNADP+to

铁氧化还原蛋nt“z-scheme”photosystemsIandADP+ Non-cyclic&cyclicThemechanismisverysimilartothatofoxidativeHowtheLightReactionsGenerateATPandNoncyclicPhotophosphorylation(非环式光合磷酸化PhotoexcitationofPSIandPSIIleadsQ→H2OsplittingbyPSIIandoxidationofQH2bythecytb6fleadstoH+gradientacrossthemembranewhichdrivesATPsynthesismediatedbyChemiosmosispowersATPsynthesisinthelightCyclicPhotophosphorylation（环式光合磷酸化CarbondioxideAlsocalledcarbondioxideassimilation（CO2同化Light-independentreaction/CalvinInC3nts,allprocessesoccurinthemesophyll（RuBP）IstheCO2AcceptorCO2carboxylationphase羧化阶段or Ribulose-1,5-Bisphosphate（8L+8Sreductionphase还原阶段PGA（3-磷酸甘油酸 GAP（甘油醛-3-磷酸regenerationphase(再生阶段 见下页转醛酶转酮酶反应

StoichiometryofCO2assimilationintheCalvinForeverythreeCO2moleculesfixed,onemoleculeoftriose(glyceraldehyde3-phosphate)isproducedand9ATPand6NADPHarealternativefatesofthefixedcarbonofThemostisrecycledtoribulose1,5-glyceraldehyde3-glyceraldehyde3-AsAsasourceofBeconvertedtosucrose（蔗糖）forBestoredinthestasPhotorespiration（光呼吸mitochondrialrespiration,theoxidationofsubstratestoCO2andtheconversionofO2toH2O.photorespiration likeMitrespiration,consumesO2andproducesCO2likephotosynthesis,isdrivenbylight.--Reason：WhenRubiscocatalyzesthereactionbetweenribulose-1,5-bisphosphatewithO2insteadofCO2OccursunderthefollowingIntenseLight(highO2HighPhotorespirationisestimatedtoreducephotosyntheticefficiencyby25%protectagainstreactiveO2byconsumingO2andreleasingribulose1,5-bisphosphatecarboxylase/oxygenase（RubiscocanaddO2toRuBP,whichleadstolossofRuBP,theessentialCO2acceptorduringCO2fixationsalvagingthecarbonsfrom2-phosphoglycolate（2-磷酸乙醇酸乙醇 乙醛甘油

过氧化物酶甘氨光呼吸中的CO2Theoxygenasereationofrubisco-乙醇酸途径C4*BothconvertCO2intoa4carbon ntshavedevelopedwaystolimittheamountofphotorespirationC4CAMCarbonassimilation（碳同化）inC4manynts,growinthetropics,suchasmaize玉米,sugarcane甘蔗,andsorghum高粱mesophyllcells（叶肉细胞bundle-sheathcells（维管束鞘细胞C4nts,CO2FixationandRubiscoActivityAreSpatiallymesophyllcell（叶肉细胞ATP驱动的CO2BSC（维管束鞘细胞HowdoestheC4PathwayBundlesheathcellsarefarfromthesurface–lessO2PEPCarboxylasedoesn’thaveanaffinityforO2→allowsnttocollectalotofCO2andconcentrateitinthebundlesheathcells(whereCrassulaceanacidCrassulaceanacidmetabolism(CAM)剑 龙兰

落地 芦根 昙丹