3-Metabolism-of-Carbohydrates-大學(xué)動(dòng)物營(yíng)養(yǎng)學(xué)課件-英文版

CarbohydrateMetabolismCarbohydrateMetabolism1AnOverviewofMetabolismAnOverviewofMetabolism2MetabolismisallthechemicalreactionsthatoccurinanorganismCellularmetabolismCellsbreakdownexcesscarbohydratesfirst,thenlipids,finallyaminoacidsifenergyneedsarenotmetbycarbohydratesandfatNutrientsnotusedforenergyareusedtobuildupstructure,arestored,ortheyareexcreted40%oftheenergyreleasedincatabolismiscapturedinATP,therestisreleasedasheatMetabolismMetabolismisallthechemical33-Metabolism-of-Carbohydrates-大學(xué)動(dòng)物營(yíng)養(yǎng)學(xué)課件-英文版43-Metabolism-of-Carbohydrates-大學(xué)動(dòng)物營(yíng)養(yǎng)學(xué)課件-英文版5CellsprovidesmallorganicmoleculestomitochondriaMitochondriaproduceATPusedtoperformcellularfunctionsCellsandMitochondriaCellsprovidesmallorganicmo6MetabolismofCarbohydratesMetabolismofCarbohydrates7CarbohydrateMetabolismPrimarilyglucoseFructoseandgalactoseenterthepathwaysatvariouspointsAllcellscanutilizeglucoseforenergyproductionGlucoseuptakefrombloodtocellsusuallymediatedbyinsulinandtransportersLiveriscentralsiteforcarbohydratemetabolismGlucoseuptakeindependentofinsulinTheonlyexporterofglucoseCarbohydrateMetabolismPrimari8BloodGlucoseHomeostasisSeveralcelltypespreferglucoseasenergysource(ex.,CNS)80-100mg/dlisnormalrangeofbloodglucoseinnon-ruminantanimals45-65mg/dlisnormalrangeofbloodglucoseinruminantanimals

Usesofglucose:EnergysourceforcellsMuscleglycogenFatsynthesisifinexcessofneeds

BloodGlucoseHomeostasisSever9FatesofGlucoseFedstateStorageasglycogenLiverSkeletalmuscleStorageaslipidsAdiposetissueFastedstateMetabolizedforenergyNewglucosesynthesizedSynthesisandbreakdownoccuratalltimes

regardlessofstate...

TherelativeratesofsynthesisandbreakdownchangeFatesofGlucoseFedstateSynth10HighBloodGlucoseGlucoseabsorbedInsulin:GlucagonPancreasMuscleAdiposeCellsGlycogenGlucoseabsorbedGlucoseabsorbedimmediatelyaftereatingameal…HighBloodGlucoseGlucoseabso11GlucoseMetabolismFourmajormetabolicpathways:EnergystatusofbodyregulateswhichpathwaygetsenergySameinruminantsandnon-ruminantsImmediatesourceofenergyPentophosphatepathwayGlycogensynthesisinliver/musclePrecursorfortriacylglycerolsynthesisGlucoseMetabolismFourmajorm12FateofAbsorbedGlucose1stPriority:glycogenstorageStoredinmuscleandliver2ndPriority:provideenergyOxidizedtoATP3rdPriority:storedasfatOnlyexcessglucoseStoredastriglyceridesinadiposeFateofAbsorbedGlucose1stPr13GlucoseUtilizationGlucosePyruvateRibose-5-phosphateGlycogenEnergyStoresPentosePhosphatePathwayGlycolysisAdiposeGlucoseUtilizationGlucosePyru14GlucoseUtilizationGlucosePyruvateRibose-5-phosphateGlycogenEnergyStoresPentosePhosphatePathwayGlycolysisAdiposeGlycogenesisGlucoseUtilizationGlucosePyru15Liver7–10%ofwetweightUseglycogentoexportglucosetothebloodstreamwhenbloodsugarislowGlycogenstoresaredepletedafter

approximately24hrsoffasting(inhumans)DenovosynthesisofglucoseforglycogenGlycogenesisLiverGlycogenesis16GlycogenesisSkeletalmuscle1%ofwetweightMoremusclethanliver,thereforemoreglycogeninmuscle,overallUseglycogen(i.e.,glucose)forenergyonly(noexportofglucosetoblood)Usealready-madeglucoseforsynthesisofglycogenGlycogenesisSkeletalmuscle17GlucoseUtilizationGlucosePyruvateRibose-5-phosphateGlycogenEnergyStoresPentosePhosphatePathwayGlycolysisAdiposeGlucoseUtilizationGlucosePyru18GlycolysisSequenceofreactionsthatconvertsglucoseintopyruvate

RelativelysmallamountofenergyproducedGlycolysisreactionsoccurincytoplasmDoesnotrequireoxygenGlucose→Pyruvate→Lactate(animals)Acetyl-CoA(TCAcycle)Ethanol(yeast)GlycolysisSequenceofreaction19GlycolysisGlucose+2ADP+2Pi

2Lactate+2ATP+2H2OGlycolysisGlucose+2ADP+220AdenosineTri-Phosphate(ATP)Linkbetweenenergyreleasingandenergyrequiringmechanisms“rechargeablebattery”ADP+P+EnergyATPAdenosineTri-Phosphate(ATP)L21MechanismsofATPFormationSubstrate-levelphosphorylationSubstratetransfersaphosphategroupdirectlyRequiresenzymesPhosphocreatine+ADPCreatine+ATPOxidativephosphorylationMethodbywhichmostATPformedSubstratetransferselectronstotransporterwhichenterstheelectrontransportchainMechanismsofATPFormationSub22FirstReactionofGlycolysisTrapsglucoseincells(irreversibleinmusclecells)Hexokinaseisusedbymostplants,animals,andmicrobestophosphorylateglucoseGlucokinaseinhepatictissueCowsdonothavehexokinase

FirstReactionofGlycolysisTr23Glycolysis-SummaryGlucose2Pyruvate2ATP2ADP4ADP4ATP2NAD2NADH+HGlycolysis-SummaryGlucose2P24PyruvateMetabolismThreefatesofpyruvate:Conversiontolactate(anaerobic)Conversiontoalanine(aminoacid)EntryintotheTCAcycleviapyruvatedehydrogenasepathwayPyruvateMetabolismThreefates25PyruvateMetabolismThreefatesofpyruvate:

Conversiontolactate(anaerobic)Conversiontoalanine(aminoacid)EntryintotheTCAcycleviapyruvatedehydrogenasepathwayPyruvateMetabolismThreefates26AnaerobicMetabolismofPyruvateProblem:Duringglycolysis,NADHisformedfromNAD+WithoutO2,NADHcannotbeoxidizedtoNAD+NomoreNAD+AllconvertedtoNADHWithoutNAD+,glycolysisstops…AnaerobicMetabolismofPyruva27AnaerobicMetabolismofPyruvateSolution:TurnNADHbacktoNAD+bymakinglactate(lacticacid)(oxidized)(reduced)(oxidized)(reduced)AnaerobicMetabolismofPyruva28AnaerobicMetabolismofPyruvateATPyieldTwoATPs(net)areproduced

intheanaerobicbreakdownofoneglucoseThe2NADHsareusedtoreduce2pyruvate

to2lactateReactionisfastanddoesn’trequireoxygenAnaerobicMetabolismofPyruva29PyruvateMetabolism-AnaerobicPyruvateLactateNADHNAD+LactateDehydrogenaseLactatecanbetransportedbybloodtoliverandusedingluconeogenesisPyruvateMetabolism-Anaerobi30CoriCycleLactateisconvertedtopyruvateintheliverCoriCycleLactateisconverted31PyruvateMetabolismThreefatesofpyruvate:Conversiontolactate(anaerobic)

Conversiontoalanine(aminoacid)EntryintotheTCAcycleviapyruvatedehydrogenasepathwayPyruvateMetabolismThreefates32PyruvatemetabolismConverttoalanineandexporttobloodKetoacid AminoacidPyruvatemetabolismConvertto33PyruvateMetabolismThreefatesofpyruvate:Conversiontolactate(anaerobic)Conversiontoalanine(aminoacid)

EntryintotheTCAcycleviapyruvatedehydrogenasepathwayPyruvateMetabolismThreefates34PyruvateDehydrogenaseComplex(PDH)PreparespyruvatetoentertheTCAcycleElectronTransportChainTCACycleAerobicConditionsPyruvateDehydrogenaseComplex35PDH-SummaryPyruvateAcetylCoA2NAD2NADH+HCO2PDH-SummaryPyruvateAcetylCo36TCACycleInaerobicconditionsTCAcyclelinkspyruvatetooxidativephosphorylationOccursinmitochondriaGenerates90%ofenergyreleasedfromfeedStrategyistooxidizeacetyl-CoAtoCO2andcaptureenergyasNADH(FADH2)andATP

Metabolizescarbohydrate,protein,andfatTCACycleInaerobicconditions373-Metabolism-of-Carbohydrates-大學(xué)動(dòng)物營(yíng)養(yǎng)學(xué)課件-英文版38TCACycle-SummaryAcetylCoA3NAD3NADH+H1FAD1FADH21ADP1ATPTCACycle-SummaryAcetylCoA339OxidativePhosphorylationOxidativePhosphorylation40Requirescoenzymes(NADandFAD)asH+carriersandconsumesoxygenKeyreactionstakeplaceintheelectrontransportsystem(ETS)CytochromesoftheETSpassH2’stooxygen,formingwaterThebasicchemicalreactionis:

2H2+O2

2H2OOxidativePhosphorylationandtheElectronTransportSystemRequirescoenzymes(NADandFA41OxidationandElectronTransportOxidationofnutrientsreleasesstoredenergyFeeddonatesH+H+’stransferredtoco-substrateNAD++2H++2e-NADH+H+

FAD+2H++2e-FADH2OxidationandElectronTranspo42So,WhatGoestotheETS???Fromeachmoleculeofglucoseenteringglycolysis:Fromglycolysis:2NADHFromtheTCApreparationstep(pyruvatetoacetyl-CoA):2NADHFromTCAcycle(TCA):6NADHand2FADH2TOTAL:10NADH+2FADH2So,WhatGoestotheETS???Fro43ElectronTransportChainNADH+H+andFADH2enterETCTravelthroughcomplexesI–IVH+flowthroughETCandeventuallyattachtoO2formingwaterNADH+H+3ATPFADH22ATPElectronTransportChainNADH+44ElectronTransportChainElectronTransportChain45TotalATPfromGlucoseAnaerobicglycolysis–2ATP+2NADHAerobicmetabolism–glycolysis+TCA

31ATPfrom1glucosemoleculeTotalATPfromGlucoseAnaerobi46VolatileFattyAcidsProducedbybacteriainthefermentationofpyruvateProvidesimportantenergysourcesforanimals,particularlyruminantsorthosethatrelyoncelluloseasakeycarbohydrateintheirdietThreemajorVFAsAcetateEnergysourceandforfattyacidsynthesisPropionateUsedtomakeglucosethroughgluconeogenesisButyrateEnergysourceandforfattyacidsynthesisSomeuseandmetabolism(alterations)byrumenwallandliverbeforebeingavailabletoothertissuesVolatileFattyAcidsProducedb47UseofVFAforEnergyEnterTCAcycletobeoxidizedAceticacidYields10ATPPropionicacidYields18ATPButyricacidYields27ATPLittlebutyrateentersbloodUseofVFAforEnergyEnterTCA48UtilizationofVFAinMetabolismAcetate

EnergyCarbonsourceforfattyacids

Adipose Mammarygland

NotusedfornetsynthesisofglucosePropionate

EnergyPrecursorofglucoseButyrate

EnergyCarbonsourceforfattyacids-mammaryUtilizationofVFAinMetaboli49EffectofVFAonEndocrineSystemPropionateIncreasesbloodglucoseStimulatesreleaseofinsulinButyrateNotusedforsynthesisofglucoseStimulatesreleaseofinsulinStimulatesreleaseofglucagonIncreasesbloodglucoseAcetateNotusedforsynthesisofglucoseDoesnotstimulatereleaseofinsulinGlucoseStimulatesreleaseofinsulinEffectofVFAonEndocrineSys50GlucoseUtilizationGlucosePyruvateRibose-5-phosphateGlycogenEnergyStoresPentosePhosphatePathwayGlycolysisAdiposeGlucoseUtilizationGlucosePyru51PentosePhosphatePathwaySecondarymetabolismofglucoseProducesNADPHSimilartoNADHRequiredforfattyacidsynthesisGeneratesessentialpentosesRiboseUsedforsynthesisofnucleicacidsPentosePhosphatePathwaySecon52PentosePhosphatePathwayGlucose-6-phosphate6-Phospho-glucono-lactone6-Phospho-gluconateD-Ribulose-5-phosphateD-Ribose-5-phosphateRNAorDNAPentosePhosphatePathwayGluco53GlucoseUtilizationGlucosePyruvateRibose-5-phosphateGlycogenEnergyStoresPentosePhosphatePathwayGlycolysisAdiposeGlucoseUtilizationGlucosePyru54EnergyStorageEnergyfromexcesscarbohydrates(glucose)storedaslipidsinadiposetissueAcetyl-CoA(fromTCAcycle)shuntedtofattyacidsynthesisintimesofenergyexcessDeterminedbyATP:ADPratiosHighATP,acetyl-CoAgoestofattyacidsynthesisLowATP,acetylCoAentersTCAcycletogenerateMOREATPEnergyStorageEnergyfromexce55FatesofGlucoseFedstateStorageasglycogenLiverSkeletalmuscleStorageaslipidsAdiposetissueFastedstateMetabolizedforenergyNewglucosesynthesizedSynthesisandbreakdownoccuratalltimes

regardlessofstate...

TherelativeratesofsynthesisandbreakdownchangeFatesofGlucoseFedstateSynth56GluconeogenesisNecessaryprocessGlucoseisanimportantfuelCentralnervoussystemRedbloodcellsNotsimplyareversalofglycolysisInsulinandglucagonareprimaryregulatorsGluconeogenesisNecessaryproce57GluconeogenesisVitalforcertainanimalsRuminantspeciesandotherpre-gastricfermentersConvertcarbohydratetoVFAinrumenLittleglucoseabsorbedfromsmallintestineVFAcannotfuelCNSandRBCFelinespeciesDietconsistsprimarilyoffatandproteinLittletonoglucoseabsorbedGlucoseconservationandgluconeogenesisarevitaltosurvivalGluconeogenesisVitalforcerta58FastingSituationinNon-RuminantsWheredoesrequiredglucosecomefrom?

GlycogenolysisLipolysisProteolysisBreakdownormobilizationofglycogenstoredbyglucagonGlucagon-hormonesecretedbypancreasduringtimesoffastingMobilizationoffatstoresstimulatedbyglucagonandepinephrineTriglyceride=glycerol+3freefattyacidsGlycerolcanbeusedasaglucoseprecursorThebreakdownofmuscleproteinwithreleaseofaminoacidsAlaninecanbeusedasaglucoseprecursor

FastingSituationinNon-Rumin59LowBloodGlucoseProteinsBrokenDownInsulin:GlucagonPancreasMuscleAdiposeCellsGlycogenGlycerol,fattyacidsreleasedGlucosereleasedInafastedstate,substratesforglucosesynthesis(gluconeogenesis)arereleasedfrom“storage”…LowBloodGlucoseProteinsBrok60GluconeogenesisSynthesisofglucosefromnon-carbohydrateprecursorsduringfastinginmonogastricsOccursprimarilyinliver,butcanalsooccurinkidneysandsmallintestine

GlycerolAminoacidsLactatePyruvatePropionateThereisnoglucosesynthesisfromfattyacidsSupplycarbonskeletonGluconeogenesisSynthesisofg61CarbohydrateComparisonPrimaryenergysubstratePrimarysubstrateforfatsynthesisExtentofglucoseabsorptionfromgutMOSTmonogastrics=glucoseRuminant/pre-gastricfermenters=VFAMOSTmonogastrics=glucoseRuminant=acetateMOSTmonogastrics=extensiveRuminant=littletononeCarbohydrateComparisonPrimary62CarbohydrateComparisonCellulardemandforglucoseImportanceofgluconeogenesisKetoneproductionNonruminant=highRuminant=highMOSTmonogastrics=lessimportantRuminant=veryimportantMOSTmonogastrics=abnormalsituationRuminant=normalsituationCarbohydrateComparisonCellula63CarbohydrateMetabolismCarbohydrateMetabolism64AnOverviewofMetabolismAnOverviewofMetabolism65MetabolismisallthechemicalreactionsthatoccurinanorganismCellularmetabolismCellsbreakdownexcesscarbohydratesfirst,thenlipids,finallyaminoacidsifenergyneedsarenotmetbycarbohydratesandfatNutrientsnotusedforenergyareusedtobuildupstructure,arestored,ortheyareexcreted40%oftheenergyreleasedincatabolismiscapturedinATP,therestisreleasedasheatMetabolismMetabolismisallthechemical663-Metabolism-of-Carbohydrates-大學(xué)動(dòng)物營(yíng)養(yǎng)學(xué)課件-英文版673-Metabolism-of-Carbohydrates-大學(xué)動(dòng)物營(yíng)養(yǎng)學(xué)課件-英文版68CellsprovidesmallorganicmoleculestomitochondriaMitochondriaproduceATPusedtoperformcellularfunctionsCellsandMitochondriaCellsprovidesmallorganicmo69MetabolismofCarbohydratesMetabolismofCarbohydrates70CarbohydrateMetabolismPrimarilyglucoseFructoseandgalactoseenterthepathwaysatvariouspointsAllcellscanutilizeglucoseforenergyproductionGlucoseuptakefrombloodtocellsusuallymediatedbyinsulinandtransportersLiveriscentralsiteforcarbohydratemetabolismGlucoseuptakeindependentofinsulinTheonlyexporterofglucoseCarbohydrateMetabolismPrimari71BloodGlucoseHomeostasisSeveralcelltypespreferglucoseasenergysource(ex.,CNS)80-100mg/dlisnormalrangeofbloodglucoseinnon-ruminantanimals45-65mg/dlisnormalrangeofbloodglucoseinruminantanimals

Usesofglucose:EnergysourceforcellsMuscleglycogenFatsynthesisifinexcessofneeds

BloodGlucoseHomeostasisSever72FatesofGlucoseFedstateStorageasglycogenLiverSkeletalmuscleStorageaslipidsAdiposetissueFastedstateMetabolizedforenergyNewglucosesynthesizedSynthesisandbreakdownoccuratalltimes

regardlessofstate...

TherelativeratesofsynthesisandbreakdownchangeFatesofGlucoseFedstateSynth73HighBloodGlucoseGlucoseabsorbedInsulin:GlucagonPancreasMuscleAdiposeCellsGlycogenGlucoseabsorbedGlucoseabsorbedimmediatelyaftereatingameal…HighBloodGlucoseGlucoseabso74GlucoseMetabolismFourmajormetabolicpathways:EnergystatusofbodyregulateswhichpathwaygetsenergySameinruminantsandnon-ruminantsImmediatesourceofenergyPentophosphatepathwayGlycogensynthesisinliver/musclePrecursorfortriacylglycerolsynthesisGlucoseMetabolismFourmajorm75FateofAbsorbedGlucose1stPriority:glycogenstorageStoredinmuscleandliver2ndPriority:provideenergyOxidizedtoATP3rdPriority:storedasfatOnlyexcessglucoseStoredastriglyceridesinadiposeFateofAbsorbedGlucose1stPr76GlucoseUtilizationGlucosePyruvateRibose-5-phosphateGlycogenEnergyStoresPentosePhosphatePathwayGlycolysisAdiposeGlucoseUtilizationGlucosePyru77GlucoseUtilizationGlucosePyruvateRibose-5-phosphateGlycogenEnergyStoresPentosePhosphatePathwayGlycolysisAdiposeGlycogenesisGlucoseUtilizationGlucosePyru78Liver7–10%ofwetweightUseglycogentoexportglucosetothebloodstreamwhenbloodsugarislowGlycogenstoresaredepletedafter

approximately24hrsoffasting(inhumans)DenovosynthesisofglucoseforglycogenGlycogenesisLiverGlycogenesis79GlycogenesisSkeletalmuscle1%ofwetweightMoremusclethanliver,thereforemoreglycogeninmuscle,overallUseglycogen(i.e.,glucose)forenergyonly(noexportofglucosetoblood)Usealready-madeglucoseforsynthesisofglycogenGlycogenesisSkeletalmuscle80GlucoseUtilizationGlucosePyruvateRibose-5-phosphateGlycogenEnergyStoresPentosePhosphatePathwayGlycolysisAdiposeGlucoseUtilizationGlucosePyru81GlycolysisSequenceofreactionsthatconvertsglucoseintopyruvate

RelativelysmallamountofenergyproducedGlycolysisreactionsoccurincytoplasmDoesnotrequireoxygenGlucose→Pyruvate→Lactate(animals)Acetyl-CoA(TCAcycle)Ethanol(yeast)GlycolysisSequenceofreaction82GlycolysisGlucose+2ADP+2Pi

2Lactate+2ATP+2H2OGlycolysisGlucose+2ADP+283AdenosineTri-Phosphate(ATP)Linkbetweenenergyreleasingandenergyrequiringmechanisms“rechargeablebattery”ADP+P+EnergyATPAdenosineTri-Phosphate(ATP)L84MechanismsofATPFormationSubstrate-levelphosphorylationSubstratetransfersaphosphategroupdirectlyRequiresenzymesPhosphocreatine+ADPCreatine+ATPOxidativephosphorylationMethodbywhichmostATPformedSubstratetransferselectronstotransporterwhichenterstheelectrontransportchainMechanismsofATPFormationSub85FirstReactionofGlycolysisTrapsglucoseincells(irreversibleinmusclecells)Hexokinaseisusedbymostplants,animals,andmicrobestophosphorylateglucoseGlucokinaseinhepatictissueCowsdonothavehexokinase

FirstReactionofGlycolysisTr86Glycolysis-SummaryGlucose2Pyruvate2ATP2ADP4ADP4ATP2NAD2NADH+HGlycolysis-SummaryGlucose2P87PyruvateMetabolismThreefatesofpyruvate:Conversiontolactate(anaerobic)Conversiontoalanine(aminoacid)EntryintotheTCAcycleviapyruvatedehydrogenasepathwayPyruvateMetabolismThreefates88PyruvateMetabolismThreefatesofpyruvate:

Conversiontolactate(anaerobic)Conversiontoalanine(aminoacid)EntryintotheTCAcycleviapyruvatedehydrogenasepathwayPyruvateMetabolismThreefates89AnaerobicMetabolismofPyruvateProblem:Duringglycolysis,NADHisformedfromNAD+WithoutO2,NADHcannotbeoxidizedtoNAD+NomoreNAD+AllconvertedtoNADHWithoutNAD+,glycolysisstops…AnaerobicMetabolismofPyruva90AnaerobicMetabolismofPyruvateSolution:TurnNADHbacktoNAD+bymakinglactate(lacticacid)(oxidized)(reduced)(oxidized)(reduced)AnaerobicMetabolismofPyruva91AnaerobicMetabolismofPyruvateATPyieldTwoATPs(net)areproduced

intheanaerobicbreakdownofoneglucoseThe2NADHsareusedtoreduce2pyruvate

to2lactateReactionisfastanddoesn’trequireoxygenAnaerobicMetabolismofPyruva92PyruvateMetabolism-AnaerobicPyruvateLactateNADHNAD+LactateDehydrogenaseLactatecanbetransportedbybloodtoliverandusedingluconeogenesisPyruvateMetabolism-Anaerobi93CoriCycleLactateisconvertedtopyruvateintheliverCoriCycleLactateisconverted94PyruvateMetabolismThreefatesofpyruvate:Conversiontolactate(anaerobic)

Conversiontoalanine(aminoacid)EntryintotheTCAcycleviapyruvatedehydrogenasepathwayPyruvateMetabolismThreefates95PyruvatemetabolismConverttoalanineandexporttobloodKetoacid AminoacidPyruvatemetabolismConvertto96PyruvateMetabolismThreefatesofpyruvate:Conversiontolactate(anaerobic)Conversiontoalanine(aminoacid)

EntryintotheTCAcycleviapyruvatedehydrogenasepathwayPyruvateMetabolismThreefates97PyruvateDehydrogenaseComplex(PDH)PreparespyruvatetoentertheTCAcycleElectronTransportChainTCACycleAerobicConditionsPyruvateDehydrogenaseComplex98PDH-SummaryPyruvateAcetylCoA2NAD2NADH+HCO2PDH-SummaryPyruvateAcetylCo99TCACycleInaerobicconditionsTCAcyclelinkspyruvatetooxidativephosphorylationOccursinmitochondriaGenerates90%ofenergyreleasedfromfeedStrategyistooxidizeacetyl-CoAtoCO2andcaptureenergyasNADH(FADH2)andATP

Metabolizescarbohydrate,protein,andfatTCACycleInaerobicconditions1003-Metabolism-of-Carbohydrates-大學(xué)動(dòng)物營(yíng)養(yǎng)學(xué)課件-英文版101TCACycle-SummaryAcetylCoA3NAD3NADH+H1FAD1FADH21ADP1ATPTCACycle-SummaryAcetylCoA3102OxidativePhosphorylationOxidativePhosphorylation103Requirescoenzymes(NADandFAD)asH+carriersandconsumesoxygenKeyreactionstakeplaceintheelectrontransportsystem(ETS)CytochromesoftheETSpassH2’stooxygen,formingwaterThebasicchemicalreactionis:

2H2+O2

2H2OOxidativePhosphorylationandtheElectronTransportSystemRequirescoenzymes(NADandFA104OxidationandElectronTransportOxidationofnutrientsreleasesstoredenergyFeeddonatesH+H+’stransferredtoco-substrateNAD++2H++2e-NADH+H+

FAD+2H++2e-FADH2OxidationandElectronTranspo105So,WhatGoestotheETS???Fromeachmoleculeofglucoseenteringglycolysis:Fromglycolysis:2NADHFromtheTCApreparationstep(pyruvatetoacetyl-CoA):2NADHFromTCAcycle(TCA):6NADHand2FADH2TOTAL:10NADH+2FADH2So,WhatGoestotheETS???Fro106ElectronTransportChainNADH+H+andFADH2enterETCTravelthroughcomplexesI–IVH+flowthroughETCandeventuallyattachtoO2formingwaterNADH+H+3ATPFADH22ATPElectronTransportChainNADH+107ElectronTransportChainElectronTransportChain108TotalATPfromGlucoseAnaerobicglycolysis–2ATP+2NADHAerobicmetabolism–glycolysis+TCA

31ATPfrom1glucosemoleculeTotalATPfromGlucoseAnaerobi109VolatileFattyAcidsProducedbybacteriainthefermentationofpyruvateProvidesimportantenergysourcesforanimals,particularlyruminantsorthosethatrelyoncelluloseasakeycarbohydrateintheirdietThreemajorVFAsAcetateEnergysourceandforfattyacidsynthesisPropionateUsedtomakeglucosethroughgluconeogenesisButyrateEnergysourceandforfattyacidsynthesisSomeuseandmetabolism(alterations)byrumenwallandliverbeforebeingavailabletoothertissuesVolatileFattyAcidsProducedb110UseofVFAforEnergyEnterTCAcycletobeoxidizedAceticacidYields10ATPPropionicacidYields18ATPButyricacidYields27ATPLittlebutyrateentersbloodUseofVFAforEnergyEnterTCA111UtilizationofVFAinMetabolismAcetate

EnergyCarbonsourceforfattyacids

Adipose Mammarygland

NotusedfornetsynthesisofglucosePropionate

EnergyPrecursorofglucoseButyrate

EnergyCarbonsourceforfattyacids-mammaryUtilizationofVFAinMetaboli112EffectofVFAonEndocrineSystemPropionateIncreasesbloodglucoseStimulatesreleaseofinsulinButyrateNotusedforsynthesisofglucoseStimulatesreleaseofinsulinStimulatesreleaseofglucagonIncreasesbloodglucoseAcetateNotusedforsynthesisofglucoseDoesnotstimulatereleaseofinsulinGlucoseStimulatesreleaseofinsulinEffectofVFAonEndocrineSys113GlucoseUtilizationGlucosePyruvateRibose-5-phosphateGlycogenEnergyStoresPentosePhosphatePathwayGlycolysisAdiposeGlucoseUtilizationGlucosePyru114PentosePhosphatePathwaySecondarymetabolismofglucoseProducesNADPHSimilartoNADHRequiredforfattyacidsynthesisGeneratesessentialpentosesRiboseUsedforsynthesisofnucleicacidsPentosePhosphatePathwaySecon115PentosePhosphatePathwayGlucose-6-phosphate6-Phospho-glucono-lactone6-Phospho-gluconateD-Ribulose-5-phosphateD-Ribose-5-phosphateRNAorDNAPentosePhosphatePathwayGluco116GlucoseUtilizationGlucosePyruvateRibose-5-phosphateGlycogenEnergyStoresPentosePhosphatePathwayGlycolysisAdiposeGlucoseUtilizationGlucosePyru117EnergyStorageEnergyfromexcesscarbohydrates(glucose)storedaslipidsinadiposetissueAcetyl-CoA(fromTCAcycle)shuntedtofattyacidsynthesisintimesofenergyexcessDeterminedbyATP:ADPratios