發(fā)明與專利法律制度課件(-110張)

Mitochondrialmoleculargenetics1精選課件pptMitochondrialmoleculargenetiMitochondrialmoleculargeneticsMitochondriaarethemainsiteofATPsynthesisineukaryotecellsandassucharevitalforthehealthandsurvivalofthecellTheyarealsooneofthesitesatwhichapoptosisismediatedTheselectureswillexplorethemoleculargeneticsofmitochondria,howtheyaremade,thestructureoftheirgenome,howtheyevolved,andhowmitochondrialgeneexpressioniscontrolled.2精選課件pptMitochondrialmoleculargenetiMitochondrialmoleculargenetics?focusonmitochondria:briefoverviewoftheirfunctionandstructure?mtDNAstructureandreplication: -animals -yeast -plants?inheritanceofmitochondria -petitemutantsofyeast?biogenesisofmitochondriabyfission3精選課件pptMitochondrialmoleculargenetiMITOCHONDRIA?essentialforcelllife -ATPsynthesis -manymetabolicintermediates?essentialforcelldeath-unprogrammeddeath:necrosis

(eg,duetolossofenergystatus)-programmedcelldeath

(apoptosis-controlledcelldestruction)4精選課件pptMITOCHONDRIA?essentialforce?Twomembranes?Innermembraneinvaginated?Numbersofmitochondriapercellvarybutusually100s/cellMatrixcontainstheTCAcycle(andother)solubleenzymesInnermembranecontainsmetabolitetransportersandtheelectrontransportchainMitochondrialstructure5精選課件ppt?TwomembranesMatrixcontainsTheribosomescanactuallybevisualizedinsomemitochondria.Inthesefigures,theyareseeninthematrixassmalldarkbodies.DNAcanalsobevisualizedinmitochondria.TheDNAiscircularandresemblesthatofabacteriuminitsbasicstructure.

MitochondriaalsohavetheirownribosomesandtRNA: ?22tRNAs ?rRNAs(16Sand12S) 6精選課件pptTheribosomescanactuallybeMitochondriacontainDNAmoleculeswithanassortmentofgenes.MitochondrialgeneticsystemconsistofDNAandthemolecularmachineryneededtoreplicateandexpressthegenescontainedinthisDNA.Thismachineryincludesthemacromoleculesneededfortranscriptionandtranslation.Mitochondriaevenpossesstheirownribosomes.Manyofthesemacromoleculesareencodedbymitochondrialgenes,butsomeareencodedbynucleargenesandarethereforeimportedfromthecytosol.7精選課件pptMitochondriacontainDNAmolecMitochondriahavetheirownDNAandRibosomesMitochondriahavesomeoftheirownDNA,ribosomes,andcanmakemanyoftheirownproteins.TheDNAiscircularandliesinthematrixinstructurescalled"nucleoids".

Eachnucleoidmaycontain4-5copiesofthemitochondrialDNA(mtDNA).mitochondrialDNA8精選課件pptMitochondriahavetheirownDNMitochondrialDNA(mtDNA)mtDNAwasdiscoveredinthe1960s;revealedasDNA-likefiberswithinmitochondria.ThecompletenucleotidesequencesofmtDNAmoleculesfrommanydifferentspecieshavenowbeendetermined.mtDNAvaryenormouslyinsize,fromabout6kbinPlasmodiumto2500kbinsomeofthefloweringplants..EachmitochondrionappearstocontainseveralcopiesofDNA.

9精選課件pptMitochondrialDNA(mtDNA)mtDNAMitochondrialDNA(mtDNA)Inavertebrateoocyte,forexample,ithasbeenestimatedthatasmanyas100millioncopiesofthemtDNAarepresent.Somaticcells,however,havefewercopies,perhapslessthan1000.MostmtDNAmoleculesarecircular,butinsomespecies,suchasalgaChlamydomonasreinhardtii萊茵衣藻

,theyarelinear.Inthevertebrates37distinctgenesarepackedintoa16to17-kbcircleleavinglittleornospacebetweengenes.10精選課件pptMitochondrialDNA(mtDNA)Ina

MITOCHONDRIALDNA(YELLOW)INTHEUNICELLULARORGANISMEUGLENAGRACILIS.THENUCLEARDNA(RED)ISALSOVISIBLE.11精選課件pptMITOCHONDRIALDNA(YELLOW)INPlantmtDNAInsomeofthefloweringplantsanunknownnumberofgenesaredispersedoveraverylargecircularDNAmoleculehundredsorthousandsofkilobaseinsize.Intheseplantsthemitochondrialgenesmaybecomeseparatedontodifferentcircularmoleculesbyaprocessofintramolecularrecombination.12精選課件pptPlantmtDNAInsomeofthefloPlantmtDNAThisrecombinationismediatedbyrepetitivesequenceslocatedinthemtDNA.Anexchangebetweentwooftherepetitivesequencescanpartitionthe“master”mtDNAcircleintotwosmallercircle,aprocessthatsuperficiallyresemblestheexcisionofalambdaprophagefromE.colichromosome.Insomespecies,severalDNAcirclesofdifferentsizesareformedbyrecombinationbetweenpairsofrepetitivesequenceslocatedatdifferentpositionsaroundthemasterDNAcircle.Thesemoleculesisdifficulttostudy,andmoreresearchisneededtoelucidatethemechanismthatproducesthem.13精選課件pptPlantmtDNAThisrecombinationIntramolecularrecombinationinthemtDNAoftheChinesecabbage,Brassicacampestris油菜.RecombinationbetweentherepeatedelementsinthelargecircularDNAmoleculepartitionsthismoleculeintotwosmallerones.Alternatively,therepeatedelementsinthetwosmallmoleculesmayrecombinewitheachothertoproduceasinglelargemolecule.14精選課件pptIntramolecularrecombinationiThestructureofmtDNAThestructureofmtDNAmoleculeshasbeenstudiedbyDNAsequencing.AnimalmtDNAissmallandcompact.Inhumanbeings,forexample,themtDNAis16,659basepairslongandcontains37genes,includingtwothatencoderibosomalRNAs,22encodetransferRNAs,and13thatencodepolypeptidesinvolvedinoxidativephosphorylation,theprocessthatmitochondriausetorecruitenergy.Inmice,cattle,andfrogs,themtDNAissimilartothatofhumanbeings–anindicationofabasicconservationofstructurewithinthevertebratesubphylum.15精選課件pptThestructureofmtDNAThestruMapofhumanmtDNAshowingthepatternoftranscription.GenesontheinnercirclearetranscribedfromtheLstrandoftheDNA,whereasgenesontheoutercirclearetranscribedfromtheHstrandoftheDNA.Arrowsshowthedirectionoftranscription.ND1-6aregenesencodingsubunitsoftheenzymeNADHreductase;thetRNAgenesinthemtDNAareindicatedbyabbreviationsfortheaminoacids.16精選課件pptMapofhumanmtDNAshowingtheThestructureofmtDNAInvertebratemtDNA

isaboutthesamesizeasvertebratemtDNA,butithasasomewhatdifferentgeneticorganization.ThesedifferencesseemtohavebeencausedbystructuralrearrangementsofthegeneswithincircularmtDNAmolecule.17精選課件pptThestructureofmtDNAInvertebThestructureofmtDNAInfungi,themtDNAisconsiderablylargerthanitisinanimals.Yeast,forexample,possessescircularmtDNAmolecules78kblong.Thesemoleculescontainatleast33genes,including2thatencoderibosomalRNAs,23to25thatencodetransferRNAs,1thatencodesaribosomalprotein,and7encodedifferentpolypeptidesinvolvedinoxidativephosphorylation.TheyeastmtDNAislargerthananimalmtDNAbecauseseveralofitsgenescontainintronsandtherearelongnoncodingsequencesbetweensomeofthegenes.AnimalmtDNAdoesnotcontainintrons.18精選課件pptThestructureofmtDNAInfungiThestructureofmtDNAPlantmtDNAismuchlargerthanthemtDNAofothersorganisms.Itisalsomorevariableinstructure.TheseconclusionscomefromcrudephysicalandchemicalanalysisandfromDNAsequencing.\OneofthefirstplantmtDNAstobesequencedisfromtheliverwort地錢

,Marchantiapolymorpha.ThemtDNAfromthisprimitive,nonvascular(非維管)

plantisa186-kbcircularmoleculewith94substantialopenreadingframes(ORFs),somecorrespondingtoknowngenesandothershavingstillunassignedgeneticfunctions.ThelatterORFsarethereforecalledURFs,forunassignedreadingframes.32distinctintronshavebeenfoundintheMarchantiamtDNA,accountingforabout20%ofthemolecule.Invascular(維管)

plants,themtDNAislargerthanitisinMarchantia;forexample,itisa570-kbcircularmoleculeinmaizeanda300-kbcircleinthewatermelon西瓜

.19精選課件pptThestructureofmtDNAPlantmtThestructureofmtDNAHigherplantmtDNAmoleculescontainmanynoncodingsequences,includingsomethatareduplicated.TheactualnumberofgenespermtDNAmoleculeisunknown.PhysicalmappingofsomeofthesegeneshasshownthattheyarelocatedindifferentpositioninthemtDNAcirclesofdifferentspecies,evenwhenthespeciesarefairlycloselyrelated.ThisimpliesthatmtDNAofhigherplantshasundergonemanygeneticrearrangementsduringitsevolution.20精選課件pptThestructureofmtDNAHigherpExpressionofMitochondrialgenesThesimplemtDNAofvertebratesareorganizedintotwolargetranscriptionunit,eachencodingtheinformationofseveralgenes.WhenthetwostrandofhumanmtDNAareseparatedbycentrifugation,oneprovestobedenser–theHstrand(forheavy),thantheotherreferredastheL(forlight).ThepromotersfortheHandLtranscriptionunitsaresituatedjustupstreamofthephenylalaninetRNAgene.ThetranscriptsareextendedinoppositedirectionsaroundthemtDNAmolecule.21精選課件pptExpressionofMitochondrialgeThetranscriptfromtheHstrandencodes2ribosomalRNAs,14tRNAs,and12polypeptides.ThetranscriptfromtheLstrandencodes8tRNAsand1polypeptide.EachtranscriptiscleavedtoseparatethetRNAsfromtherRNAsandmRNAs,andmRNAsarepolyadenylated.EachmRNAisthentranslatedintopolypeptides,usingthemitochondrialribosomesandacombinationofnuclearandribosomaltRNAs.ExpressionofMitochondrialgenes22精選課件pptThetranscriptfromtheHstraTranslationinthemitochondriaproceedsmuchasitdoesontheribosomesofthecytosol,exceptthatsomeofthecodonshaveadifferentmeaning.AGAandAGGareterminationcodonsinmammalianmitochondria,whereasinthecytosoltheyspecifytheincorporationofarginine;UGA,whichisterminationcodoninthecytosol,isatryptophancodoninthemitochondria;andAUA,whichencodesisoleucineincytosol,isthemethionineinitiationcodoninthemitochondria.ExpressionofMitochondrialgenes23精選課件pptTranslationinthemitochoInfungiandplantsthemtDNAisorganizedintomanyseparatetranscriptionunits,somecontainingtheinformationformorethanonegene.Littleisknownaboutthedetailsoftranscription,butinyeast,themitochondrialRNApolymeraseisasinglepolypeptideencodedbyanucleargene.RNAprocessingseparatesplantmitochondrialtranscriptsintotheirconstituentpartsandalsoremovestheintrons,whicharepresentinseveralplantmitochondrialgenes.

THEMECHANICSOFTHESEEVENTSAREPOORLYUNDERSTOOD.ExpressionofMitochondrialgenes24精選課件pptInfungiandplantsthemtDNAAnotherpeculiarityofplantmitochondrialgeneexpressionisthatmanyofthemtRNAtranscriptsundergoediting;thatis,someofthenucleotidesarechangedaftertranscripthasbeensynthesized.ThemostfrequentchangeisCtoU(occasionallyUtoC).Thus,RNAeditingaltersthecompositionofcodonsinplantmitochondrialtranscript.EditingalterstheinformationthatisactuallyencodedinthemtDNAandallowsfunctionalpolypeptidestobesynthesized.Editingisnotfoundinthenonvascularplants(mossesandalgae藻類和苔蘚植物).Theeditingmechanismprobablyevolvedsometimeafterplantshadbecomeestablishedontheland.ExpressionofMitochondrialgenes25精選課件pptAnotherpeculiarityofplantmYetathirdpeculiarityofplantmitochondrialgeneexpressionisthatsomemitochondrialmRNAsareformedbytheprocessoftrans-splicing.ItoccurswhensegmentsofagenearescatteredoverthemtDNAmolecule.Eachgenesegmentistranscribedindependently,andexonsofthedifferenttranscriptsaresplicedtogetherbyinteractionsbetweentheintronsthatflankthem.ExpressionofMitochondrialgenes分子內(nèi)(intramolecular)剪接(cissplicing)以及分子間(intermolecular)剪接(transsplicing)26精選課件pptExpressionofMitochondrialgeTrans-splicinginwheatmitochondria.FourdifferentRNAscontributetothefinalmRNAencodingapolypeptideoftheenzymeNDHreductase.27精選課件pptTrans-splicinginwheatmitoch

INTERPLAYBETWEENMITOCHONDRIALANDNUCLEARGENEPRODUCTSMost–perhapsall-mitochondrialgeneproductsfunctionsolelywithinmitochondrion.However,theydonotfunctionalone.Manynucleargeneproductsareimportedtoaugmentorfacilitatetheirfunction.Manyofthepolypeptidesneededforaerobicmetabolismarealsosynthesizedincytosol(ATPase–thatisresponsibleforbindingtheenergyofaerobicmetabolismintoATP).However,becausesomeofthesubunitsofthisproteinaresynthesizedinthemitochondria,thecompleteproteinisactuallyamixtureofnuclearandmitochondrialgeneproducts.28精選課件pptINTERPLAYBETWEENMITOCHONDR

INTERPLAYBETWEENMITOCHONDRIALANDNUCLEARGENEPRODUCTSThisdual(雙重的)compositionsuggeststhatnuclearandthemitochondrialgeneticsystemsarecoordinatedinsomewaysothatequivalentamountsoftheirproductsaremade;possiblemolecularmechanismsforthiscoordinationarecurrentlyunderinvestigation.29精選課件pptINTERPLAYBETWEENMITOCHONDRKEYPOINTSmtDNAmoleculesrangefrom6-kbto2500-kbinsize,andmostofthemappeartobecircular.mtDNAmoleculescontaingenesforsomeoftheribosomalRNAs,transferRNAs,andpolypeptidesusedwithinthemitochondrion.Thestructure,organization,andexpressionofmitochondrialgenesvaryamongspecies.Insomeorganisms,thetranscriptsofmitochondrialgenesareeditedaftertheyaresynthesized.Bothmitochondrialandnucleargeneproductsareneededfornormalmitochondrialfunction.30精選課件pptKEYPOINTSmtDNAmoleculesrangmtDNAandhumandisease

Recentresearchhasdemonstratedthatseveralhumandiseasesarecausedbymitochondrialdefects,andinsomecases,thesedefectsareduetomutationsinthemtDNA.OnesuchdiseaseisLeber’shereditaryopticneuropathy(LHON),aconditioncharacterizedbythesuddenonsetofblindnessinadults.Thisdiseaseisassociatedwiththedeathoftheopticnerve(ataphysiologicallevel),andwithmutationinanyofseveralmitochondrialgenes(atamolecularlevel).Eachmutationchangesanaminoacidinoneofthemitochondrialproteins–reducingtheefficiencyofoxidativephosphorylation.Thereductionisgreatenoughtodestroythefunctionoftheopticnerveandcausetotalblindness.Itisnotknownwhythiseffectislimitedtotheopticnerve.LHONisinheritedstrictlythroughthematernalline.31精選課件pptmtDNAandhumandisease

ReceAnotherdisordercausedbyamutationinthemtDNAisaPearsonmarrow-pancreassyndrome,characterizedbyalossofbone-marrowcellsduringchildhood,isfrequentlyfatal.ItiscausedbyafairlylargedeletionsinthemtDNA.Peoplewiththissyndromealmostneverhaveaffectedparents.Thus,thecausativedeletionprobablyoccursspontaneouslyduringdevelopmentinthechildorduringoogenesisinthemother.IndividualswithPearsonsyndromeactuallyhaveamixtureofdeletedandnormalmtDNA–anexampleofmitochondrialheteroplasmy.Homoplasmicindividualshaveneverbeenobserved.

mtDNAandhumandisease32精選課件pptAnotherdisordercausedbyamThemoleculargeneticsof

ChloroplastsChloroplastscontainDNAmoleculeswithanassortmentofgenes.Chloroplastarespecializedformsofageneralclassofplantorganellescalledplastids質(zhì)體

.Botanistsdistinguishamongseveralkindsofplastids,includingchloroplasts(plastidscontainingpigments),amyloplasts(plastidscontainingstarch造粉體：一種形成淀粉的植物性白色體),andelaioplasts(油質(zhì)體

plastidscontainingoilorlipid).Allthreetypesseemtodevelopfromsmallmembrane-boundedorganellescalledproplastids前質(zhì)體,and,withinaparticularplantspecies,allseemtocontainthesameDNA.ThisDNAisgenerallyreferredtoaschloroplastDNA,abbreviatedsimplyascpDNA.33精選課件pptThemoleculargeneticsof

ChloCHLOROPLASTDNAInhigherplants,cpDNAtypicallyrangefrom120to160kbinsize,andinalgae,from85to292kb.InafewspeciesofgreenalgaethecpDNAismuchlarger,about2000kb.ThecpDNAseemstobeorganizedasaclosedcircularmolecule,butinsomespecies(withlargecpDNAs)alineararrangementcannotberuledout.ThenumberofcpDNAmoleculesinacelldependsontwofactors:thenumberofchloroplastsandthenumberofcpDNAmoleculeswithineachchloroplast.34精選課件pptCHLOROPLASTDNAInhigherplantCHLOROPLASTDNAAllcpDNAmoleculescarrybasicallythesamesetofgenes,butindifferentspeciesthesegenesarearrangedindifferentways.ThebasicgenesetincludesgenesforribosomalRNAs,transferRNAs,someribosomalproteins,variouspolypeptidecomponentsofphotosystemsthatareinvolvedincapturingsolarenergy,foursubunitsofaribulose1,5-biphosphatecarboxylase磷酸核酮糖梭化酶,andfoursubunitofachloroplast-specificRNApolymerase.MostcpDNAshaveapairoflargeinvertedrepeatsthatcontainthegenesforribosomalRNAs.Theserepeatsrangeanywherefrom10to76kbinlengthandarevariouslylocatedindifferentcpDNAmolecules.35精選課件pptCHLOROPLASTDNAAllcpDNAmolec.

GeneticorganizationofthechloroplastDNAintheliverwortMarchantiapolymorpha.Symbols:rpo,RNApolymerase;rps,ribosomalproteinsofsmallsubunit;rplandsecX,ribosomalproteinsoflargesubunit;4.5S,5S,16S,23S,rRNAsoftheindicatedsize;rbs,ribulosebisphosphatecarboxylse;psa,photosystemI;psb,photosystemII;pet,cytochromeb/fcomplex;atp,ATPsynthesis;infA,initiationfactorA;frx,iron-sulfurproteins;ndh,putativeNADHreductase;mph,chloroplastpermease(?);tRNAgenesareindicatedbyabbreviationsfortheaminoacids.36精選課件ppt.

GeneticorganizationoftheCHLOROPLASTBIOGENESISAllplastidsdevelopfromproplastids.Chloroplastsdevelopmentisstimulatedbylight,andinvolvesthetranscriptionofmanygenes,somelocatedinthenucleus.Alltheproteinsandchlorophyllpigmentsneededforphotosynthesisaremadeandtargetedtotheirappropriatelocationswithintheemergingchloroplast.Theformationsoffunctionalchloroplastsisaprocessreferredtoasbiogenesis.Onlysomeofthedetailsareknown.Lightplaysanimportantrole.Somegenesaretranscribedwhenlightisprovided.37精選課件pptCHLOROPLASTBIOGENESISAllplasCHLOROPLASTBIOGENESISAspecialclassofpigmentedproteinscalledphytochromes(光敏色素)seemstomediatethisandothersresponsestolight.Byabsorbinglightenergy,theseproteinsacquiretheabilitytotriggerotherproteinstostimulatethetranscriptionofgenesinvolvedinchloroplastbiogenesis.Theformationofchloroplastsandthemaintenanceoftheirstructureandfunctionduringthelifeofaplantdependonthecoordinatedexpressionofnuclearandchloroplastgenes.38精選課件pptCHLOROPLASTBIOGENESISAspeciaChloroplastbiogenesis.Amaturechloroplastcontainingstacks(堆)ofthylakoid類囊體membranes(grana基粒)withinitsprotoplasmicstroma(基質(zhì))developsfromaproplastidafterexposuretolight.39精選課件pptChloroplastbiogenesis.AmaKEYPOINTSChloroplastDNA(cpDNA)moleculesaretypically120to292kbinsize,andtheycontainatleast100genes.TheorganizationofcpDNAmoleculesvariesamongspeciesofplantsandalgae.Lightinduceschloroplaststodevelopfromunpigmentedplastidsthroughaprocessthatinvolvestheinterplayofchloroplastandnucleargeneproducts.40精選課件pptKEYPOINTSChloroplastDNA(cpDMitochondrialInheritanceYeasthasbeenusedextensivelytostudymitochondrialinheritance.ThereisaYeaststrain,called"Petite小型菌聚落"thathavestructurallyabnormalmitochondriathatareincapableofoxidativephosphorylation.

ThesemitochondriahavelostsomeoralloftheirDNA.Geneticcrossesbetweenpetiteandwt(wild-type)strainsshowedthatinheritanceofthistraitdidnotsegregatewithanyofthenuclearchromosomes.

41精選課件pptMitochondrialInheritance41精選課Mitochondrialinheritancefromyeastisbiparental雙親的,andbothparentcellscontributetothedaughtercellswhenthehaploidcellsfuse.

Aftermeiosisandmitosis,thereisrandomdistributionofmitochondriatodaughtercells.

Ifthefusioniswithyeastthatarepetiteandyeastthatarenot,acertainpercentageofthedaughtercellswillbe"petite".

MitochondrialInheritance42精選課件pptMitochondrialinheritancefromMitochondrialInheritanceinYeast43精選課件pptMitochondrialInheritanceinY復(fù)制分離又稱不均等的有絲分裂分離44精選課件ppt復(fù)制分離又稱不均等的有絲分裂分離44精選課件ppt復(fù)制分離在連續(xù)的細胞分裂過程中，異質(zhì)性細胞中突變型mtDNA和野生型mtDNA的比例會發(fā)生漂變，向同質(zhì)性的方向發(fā)展。分裂旺盛的細胞（如血細胞）往往有排斥突變mtDNA的趨勢，經(jīng)無數(shù)次分裂后，細胞逐漸成為只有野生型mtDNA的同質(zhì)性細胞。突變mtDNA具有復(fù)制優(yōu)勢，在分裂不旺盛的細胞（如肌細胞）中逐漸積累，形成只有突變型mtDNA的同質(zhì)性細胞。漂變的結(jié)果，表型也隨之發(fā)生改變。45精選課件ppt復(fù)制分離在連續(xù)的細胞分裂過程中，異質(zhì)性細胞中突變型mtDNAThisledtothesuggestionthatsomegeneticelementexistedinthecytoplasmandwasinheritedinadifferentmannerfromnucleargenes.Thisiscalled“non-Mendelianinheritance”or“cytoplasmicinheritance”.MitochondrialInheritanceInyeastandanimals,thisindicatedinheritanceofmitochondrialgenes:inplantsitalsoincludesinheritanceofchloroplastgenes46精選課件pptThisledtothesuggestionthaMitochondrialreplication47精選課件pptMitochondrialreplication47精選課Mitochondriareplicatemuchlikebacterialcells.Whentheygettoolarge,theyundergofission.Thisinvolvesafurrowingoftheinnerandthentheoutermembraneasifsomeonewaspinchingthemitochondrion.Thenthetwodaughtermitochondriasplit.Ofcourse,themitochondriamustfirstreplicatetheirDNA.Anelectronmicrographdepictingthefurrowingprocessisshowninthesefigures.

Mitochondrialreplicationcelldivision:randomdistributionofmitosbetweendaughtercellsmitochondrialreplication48精選課件pptMitochondriareplicatemuchliSometimesnewmitochondriaaresynthesizedincentresthatarerichinproteinsandpolyribosomesneededfortheirsynthesis.Theelectronmicrographinthefollowingfigureshowssuchacentre.Itappearsthattheclusterofmitochondriaaresittinginamatrixofproteinsandothermaterialsneededfortheirproduction.

49精選課件pptSometimesnewmitochondriaareCertainmitochondrialproteinsareneededbeforethemitochondriacandivide.TheyshowedtheresultoftheremovalofanoutermembraneproteinfrommitochondriacalledMDM10.Thisfigureshowstheresults.Themitochondriaareabletotakeincomponentsandproducemembranesandmatrixenzymes.However,fissionisnotallowedandtheresultisagiantmitochondrion.

giantmitochondrion50精選課件pptCertainmitochondrialproteinsHumanmtDNA?small,doublestrandedcircularchromosome?16,569bpintotal?nonon-codingDNA?nointrons?polycistronicreplicationwhichisinitiatedfromtheD(displacement)-loopregion?followedbysplicingoftranscripttoformmessages.Organisationofthemitochondrialchromosome51精選課件pptHumanmtDNAOrganisationofthehumanmtDNAyeastmtDNAYeastmitochondrialchromosome52精選課件ppthumanmtDNAyeastmtDNAYeast52精HumanDNA?16,569bp;?nonon-codingDNA?nointrons?polycistronicreplicationfollowedbysplicingtoformmessages.YeastmtDNA?68-75kb,similarinstructuretobacterialgenome?containsintronsandnon-regionsbetweengenes.?Sameproteinsmadeasinanimals?genestranscribedseparately53精選課件pptHumanDNA53精選課件pptDespitehavingtheirowngenome,mostmitochondrialproteinsareencodedinthenucleus,madeinthecytosolandimportedintothemitochondria.54精選課件pptDespitehavingtheirowngenomInallorganisms,onlyafewoftheproteinsofthemitochondrionareencodedbymtDNA,buttheprecisenumbervariesbetweenorganisms?Subunits1,2,and3ofcytochromeoxidase?Subunits6,8,9oftheFo

ATPase?ApocytochromebsubunitofcomplexIII?SevenNADH-CoQreductasesubunits(exceptinyeast)Thenucleusencodestheremainingproteinswhicharemadeinthecytosolandimportedintothemitochondrion.Synthesisofmitochondrialproteins55精選課件pptInallorganisms,onlyafewoPlantmtDNA?chromosomesizeismuchbiggerbutvariesdramaticallybetweenspecies(200-2000kb)?arrangedasdifferentsizecircles,sometimeswithplasmids.?TheplantmtDNAcontainschloroplastsequences,indicatingexchangeofgeneticinformationbetweenorganellesinplants.?MuchoftheplantmtDNAisnon-coding,butcodingregionsarelargerthananimalsandfungi.?Numberofproteinssynthesisednotknowndefinitelybutmorethaninanimalsandyeast(probablyabout50)56精選課件pptPlantmtDNA56精選課件pptPlantmitochondriahavespecialisedfunctions

?inleavestheyparticipateinphotorespiration

?sitesofvitaminsynthesis(vitC,folicacid,biotin)57精選課件pptPlantmitochondriahavespeciamaizemitochondrialgenome58精選課件pptmaizemitochondrialgenome58精選Inplants,respirationandphotosynthesisoperatesimultaneouslyinthelightNIGHTDAY59精選課件pptInplants,respirationandphoChloroplastsarethesiteofphotosynthesisandbelongtotheplastidfamilyoforganelles-theydevelopfromproplastidsinthelightproplastidlightthylakoidstacksamyloplast(instorageorgans)60精選課件pptChloroplastsarethesiteofpRicemitochondrialandchloroplastgenomesPlantmitochondriacontainchloroplastgenes-suggestingthatgenetictransferoccursbetweenthetwoorganelles61精選課件pptRicemitochondrialandchloropMitochondrialDNAofanimalsandfungiusesadifferentgeneticcodethanthe“universal”code62精選課件pptMitochondrialDNAofanimalsaRNAprocessinginmitochondriaPlantmitochondria“edit”theirRNAtranscripts.ThiswasfirstnoticedwhencomparingcDNAsequenceswithgenomicDNAsequences.ThemostcommonchangeistoreplaceCwithU,althoughinsomeinstancesotherchangescanoccur.Matrixenzymesarethoughttoberesponsibleforthis,butthereasonfortheeditingisnotknown.MostoftheDNAinplantmitochondriaisnon-coding,onlysomeofwhichistranscribed.RNAeditingoccurseveninnon-codingregionssuchasintrons.63精選課件pptRNAprocessinginmitochondriaMitochondriaandchloroplastsNon-codingDNAisrareinmitochondriaandchloroplasts.Mitochondriaoriginatedmorethanabillionyearsagowhenafree-livingbacterium,theclosestlivingrelativesofwhicharetheα-proteobacteria,enteredaeukaryoticcell.Bacterialendosymbiosisisalsothoughttobetheoriginofchloroplasts,withthecyanobacteria(blue-greealgae)asthemostlikelyancestors.64精選課件pptMitochondriaandchloroplastsNMitochondrialgenome(mtDNA)sizesrangefromonly6kb(kilobases)uptomorethan2000kb,withthehumanvers