第1页共9页编号：时间：2021年x月x日书山有路勤为径，学海无涯苦作舟页码：第1页共9页细胞生物学双语教案3（线粒体结构与功能）MitochondrialSubstructureMitochondriacontaintwomembranes,separatedbyaspace.Botharethetypical"unitmembrane"(railroadtrack)instructure.Insidethespaceenclosedbytheinnermembraneisthematrix.ThisappearsmoderatelydenseandonemayfindstrandsofDNA,ribosomes,orsmallgranulesinthematrix.Themitochondriaareabletocodeforpartoftheirproteinswiththesemoleculartools.Theabovecartoonshowsthediagramofthemitochondrialmembranesandtheenclosedcompartments.Howaremitochondriaorganizedtobepowerhouses?Thefoodweeatisoxidizedtoproducehigh-energyelectronsthatareconvertedtostoredenergy.Thisenergyisstoredinhighenergyphosphatebondsinamoleculecalledadenosinetriphosphate,orATP.ATPisconvertedfromadenosinediphosphatebyaddingthephosphategroupwiththehigh-energybond.Variousreactionsinthecellcaneitheruseenergy(wherebytheATPisconvertedbacktoADP,releasingthehighenergybond)orproduceit(wherebytheATPisproducedfromADP).Stepsfromglycolysistotheelectrontransportchain.Whyaremitochondria第2页共9页第1页共9页编号：时间：2021年x月x日书山有路勤为径，学海无涯苦作舟页码：第2页共9页important?LetsbreakdowneachofthestepssoyoucanseehowfoodturnsintoATPenergypacketsandwater.Thefoodweeatmustfirstbeconvertedtobasicchemicalsthatthecellcanuse.Someofthebestenergysupplyingfoodscontainsugarsorcarbohydrates...bread,forexample.Usingthisasanexample,thesugarsarebrokendownbyenzymesthatsplitthemintothesimplestformofsugarwhichiscalledglucose.Then,glucoseentersthecellbyspecialmoleculesinthemembranecalled“glucosetransporters”.Onceinsidethecell,glucoseisbrokendowntomakeATPintwopathways.Thefirstpathwayrequiresnooxygenandiscalledanaerobicmetabolism.Thispathwayiscalledglycolysisanditoccursinthecytoplasmoutsidethemitochondria.Duringglycolysis,glucoseisbrokendownintopyruvate.Otherfoodslikefatscanalsobebrokendownforuseasfuel(seefollowingcartoon).Eachreactionisdesignedtoproducesomehydrogenions(electrons)thatcanbeusedtomakeenergypackets(ATP).However,only4ATPmoleculescanbemadebyonemoleculeofglucoserunthroughthispathway.Thatiswhymitochondriaandoxygenaresoimportant.WeneedtocontinuethebreakdownprocesswiththeKreb’scycleinsidethemitochondriainordertogetenoughATPtorunallthecellfunctions.Theeventsthatoccurinsideandoutsidemitochondriaarediagrammedintheabovecartoon.PyruvateiscarriedintothemitochondriaandthereitisconvertedintoAcetylCo-AwhichenterstheKreb'scycle.Thisfirstreactionproducescarbondioxidebecauseitinvolvestheremovalofonecarbonfromthepyruvate.第3页共9页第2页共9页编号：时间：2021年x月x日书山有路勤为径，学海无涯苦作舟页码：第3页共9页HowdoestheKreb'scyclework?ThewholeideabehindrespirationinthemitochondriaistousetheKreb’scycle(alsocalledthecitricacidcycle)togetasmanyelectronsoutofthefoodweeataspossible.Theseelectrons(intheformofhydrogenions)arethenusedtodrivepumpsthatproduceATP.TheenergycarriedbyATPisthenusedforallkindsofcellularfunctionslikemovement,transport,entryandexitofproducts,division,etc.Thefollowingexplanationisverysimpleandfocusesononlythepathwayfrompyruvatethroughthecycle.However,itillustratestheprocessanditsfunctions.ToruntheKreb'scycle,youneedseveralimportantmoleculesinadditiontoalltheenzymes.Consultyourtextfordetailsabouttheenzymesthemselves.Thispresentationwillfocusontheelectrondonors,carriersandacceptors.First,youneedpyruvate,whic...
