細(xì)胞核和染色體-文稿演示

細(xì)胞核和染色體文稿演示MaincontentsSection1nuclearenvelopeandnuclearporecomplexSection2chromatinSection3chromatinstructureandgeneactivationSection4chromosomeSection5nucleolusSection6nuclearmatrix2Section4chromosome(染色體)Q:Whatisthechromosome?3Chromosome(染色體):Atsomepointduringthecelldivisionprocess,thechromatinwillbepackagedtightlyenoughthatweareabletovisualizedistinctchromosomesunderthelightmicroscope分裂期染色質(zhì)凝集而成的棒狀結(jié)構(gòu)。Q:Canyouseechromosomesunderlightmicroscope?4Chromosomenumber,size,andshape

atmetaphasearespeciesspecificSeeP343,Tab10-65Isthereacorrelationbetweenchromosomenumberandcomplexityoftheorganism?ChromosomeNumbers6

Chromosome染色體

Morphologyofthemetaphasechromosome中期染色體的形態(tài)結(jié)構(gòu)Functionalelements

染色體DNA的三種功能元件Karyotypeandchromosomebanding核型與染色體顯帶Giantchromosome巨大染色體7一、中期染色體的形態(tài)結(jié)構(gòu)

StructureofmetaphasechromosomeChromosomesaredetectedonlyoccurduringcelldivisionandnotduringallstagesofthecellcycle.Theyareintheirmostcondensedformduringmetaphase(中期)whenthesisterchromatids（姐妹染色單體）areattached.8Metaphasechromosome:ThetworeplicateddaughterDNAsareencasedinchromosomalproteinsformingsisterchromatids,whichareheldtogetherattheircentromere.9根據(jù)著絲粒在染色體上所處的位置，將中期染色體分為四種類型：metacentricchromosome（中著絲粒染色體）submetacentricchromosome（近中著絲粒染色體）acrocentricchromosome（近端著絲粒染色體）telocentricchromosome（端著絲粒染色體）10一、中期染色體的形態(tài)結(jié)構(gòu)

StructureofmetaphasechromosomeCentromere(著絲粒)&Kinetochore（動粒）Centromere（著絲粒）:HighlyrepeatedDNA+Kinetochore（動粒）11著絲粒3個結(jié)構(gòu)域Kinetochoredomain：位于著絲粒表面外板（outerplate）內(nèi)板（innerplate）中間區(qū)（interzone）纖維冠(fibrouscorona)Centraldomain:高度重復(fù)的α衛(wèi)星DNAPairingdomain：apointofattachmentbetweentwosisterchromatids中心結(jié)構(gòu)域配對結(jié)構(gòu)域動粒結(jié)構(gòu)域12SatelliteDNA(FISHimage)13ThestructureofahumanCENCentromere&Kinetochore14著絲粒的結(jié)構(gòu)1、動粒結(jié)構(gòu)域（kinetochoredomain）位于著絲粒的表面，包括內(nèi)板(innerplate)

中間間隙(middlespace),innerzone

外板(outerplate)

纖維冠(fibrouscorona)2、中央結(jié)構(gòu)域（Centraldomain）位于著絲粒結(jié)構(gòu)域的下方。其中含有高度重復(fù)的衛(wèi)星DNA。3、配對結(jié)構(gòu)域（Pairingdomain）位于著絲粒結(jié)構(gòu)的內(nèi)層，中期兩條染色單體在此處相互連結(jié)。用ACAs發(fā)現(xiàn)鑒定出來的著絲粒蛋白CENP主要有6種，即：CENP-A至F。15Centromericproteins

ProteinsassociatedwiththecentromerehavebeenidentifiedusingantibodiesfromsclerodermapatientsCENPproteinsCENP-A centromere-specifichistoneCENP-B bindscentraldomainsatelliteDNACENP-C bindskinetochoreCENP-D bindskinetochoreCENP-E kinesin-likemotor,involvedinchromatidsegregationCENP-FbindskinetochoreINCENPproteinsINCENP-A sisterchromatidassociationINCENP-B sisterchromatidassociation16一、中期染色體的形態(tài)結(jié)構(gòu)

AtypicalmitoticchromosomeatmetaphaseHumanchromosomeNo.14

2.secondaryconstriction（次縊痕）3.nucleolarorganizingregion,NOR（核仁組織區(qū)）4.Satellite（隨體）5.Telomere（端粒）1.Centromere（著絲粒）Primaryconstriction主縊痕17NOR（Nucleolarorganizerregions）

:NORisachromosomalregionaroundwhichthenucleolusforms.Thisregionistheparticularpartofachromosomethatisassociatedwithanucleolusafterthenucleusdivides.TheregioncontainsseveraltandemcopiesofribosomalRNAgenes.細(xì)胞核特定染色體的次縊痕處，含有rRNA基因的一段染色體區(qū)域，與核仁的形成有關(guān)，故稱為核仁組織區(qū)。

18NOR（Nucleolarorganizerregions）

:NotallchromosomesinagenomehaveNORs,butseveralofthemmayhave.Inhumans,theNORcontainsgenesfor5.8S,18S,and28SrRNAclusteredontheshortarmsofchromosomes13,14,15,21and22(theacrocentricchromosomes).19TheNORisresponsiblefortheformationofthenucleolusduringtelophaseandisalsothesiteofribosomalRNAsynthesis.與間期核仁的形成有關(guān)NOR（Nucleolarorganizerregions）

:20Telomeres端粒Telomeresarethephysicalendsoflineareukaryoticchromosomes.Theyconsistoftandemrepeatsofashort(6-8bp)sequencethatishighlyconservedthroughevolution.位于染色體DNA的兩端,為一富含GC的短串聯(lián)重復(fù)序列DNA組成，進(jìn)化上高度保守。2122TelomeresThetelomeresofhumansconsistofasmanyas2000repeatsofthesequence:5'TTAGGG3'.5'...TTAGGGTTAGGGTTAGGGTTAGGGTTAGGGTTAGGG..3'3'...AATCCCAATCCCAATCCCAATCCCAATCCCAATCCC..5'

Telomeresarecrucialtothelifeofthecell.Theykeeptheendsofthevariouschromosomesinthecellfromaccidentallybecomingattachedtoeachother.2324二、染色體DNA的3種功能元件

ThreefunctionalelementsinchromosomalDNA

Threefunctionalelementsarerequiredforreplicationandstableinheritanceofchromosomes25構(gòu)成染色體DNA的三種關(guān)鍵序列（keysequence）autonomouslyreplicatingDNAsequence,ARS

（自主復(fù)制DNA序列）centromericDNAsequence,CEN（著絲粒DNA序列）telomericDNAsequence,TEL（端粒DNA序列）26autonomouslyreplicatingDNAsequence,ARS結(jié)構(gòu)：富含AT的共有序列。功能：DNA復(fù)制起點，保證自我復(fù)制，ARSactasanoriginofreplication.27MultipleoriginsofreplicationinEukaryotes28CentromericDNAsequence,CENLEU合成酶基因重組到含CEN和ARS的環(huán)狀質(zhì)粒，轉(zhuǎn)染LEU合成酶合成缺陷細(xì)胞，在無LEU的培養(yǎng)基中可以生存。核心區(qū)：一個80-90bp的AT區(qū)，一個11bp的保守區(qū)。功能：將完成復(fù)制的染色體平均分配到子細(xì)胞中。TransfectedLeu-cellbyPlasmidwithsequenceProgenyoftransfectedcellMitoticsegregationConclusionGrowthwithoutLeu29telomericDNAsequence(端粒序列):FunctionsForthecompletereplicationofchromosome染色體復(fù)制的完整性Protectthechromosomesfromnucleaseinfluence免受核酸酶的影響Preventtheendsofchromosomesfromfusing免染色體端端粘合30Telomeres(端粒):由高度重復(fù)的短序列組成，高度保守。

Thetelomeresofhumansconsistofasmanyas2000repeatsofthesequence:5'TTAGGG3'.5'...TTAGGGTTAGGGTTAGGGTTAGGGTTAGGGTTAGGG..3'3'...AATCCCAATCCCAATCCCAATCCCAATCCCAATCCC..5'

作用：維持染色體的穩(wěn)定性。起細(xì)胞分裂計時器的作用。31AAAAAAAAAAAAAAAAFISH(HumanProbe):TTAGGGTelomeres(端粒):Telemerase(端粒酶)：

RNA+逆轉(zhuǎn)錄酶A32Telomere,telomeraseandcellularaging,cancercellTelomeraseisfoundingermcells,notinsomaticcells.Thetelomerelengthofadultisshorterthanthatofyounger.Telomereshorteningisthoughttoactivateasuicideprogram.So,telomereshorteningplaysakeyroleinprotectingthebodyfromcancer.90%ofhumantumorscontainanactivetelomerase.端粒核苷酸復(fù)制和基因DNA不同，每復(fù)制一次減少50~100bp，其復(fù)制要靠具有反轉(zhuǎn)錄酶性質(zhì)的端粒酶來完成，正常體細(xì)胞缺乏此酶，故隨細(xì)胞分裂而變短，細(xì)胞隨之衰老。33三、核型和染色體顯帶

karyotypeandchromosomebandingThecompletesetofchromosomesinthenormaldiploidcellsofanorganismisitskaryotype.通常將一個物種所具有的染色體數(shù)目和每一條染色體的形態(tài)特征稱核型。核型分析：對染色體進(jìn)行分組、排隊、配對并進(jìn)行形態(tài)分析的過程34HumanKaryotype12345678910111213141516171819202122XX(orXY)35Karyotypeoffemaleandmale:Thekaryotypeofthehumanfemalecontains23pairsofhomologouschromosomes:22pairsofautosomes

1pairofXchromosomesThekaryotypeofthehumanmalecontains:thesame22pairsofautosomesoneXchromosomeandoneYchromosome36染色體顯帶(chromosomebanding)用特殊的染色方法使染色體沿其長軸顯示出明暗交替或染色深淺不同的橫紋——帶。pq32112346432152131212123541213241p3137Gband:Stainingwiththetrypsin-giemsamethodrevealsaseriesofalternatinglightanddarkbandscalledGbands.Trypsin處理、giemsa染色，將染色體染成明暗相間的帶38G-bandingThedyestainsregionsofchromosomesthatarerichinthebasepairsAdenine(A)andThymine(T)producingadarkbandAT豐富的染色體節(jié)段深染39Q帶：Q顯帶技術(shù)早在1970年為Caspersson及其同事們首先用熒光染料染制染色體標(biāo)本，在熒光顯微鏡下這些染色體呈現(xiàn)暗亮不同的條紋，40Normalcell46chromosomesCancercell80chromosomesChromosomeNumberVariations41DownSyndrome/Trisomy21

Downsyndromewasoriginallydescribedin1866byJohnLangdonDown.42C-Bandingonlystainscentromericregions(著絲粒區(qū))431881年意大利的Balbiani發(fā)現(xiàn)于雙翅目搖蚊幼蟲的唾腺細(xì)胞。細(xì)胞內(nèi)特殊的、體積很大的染色體。包括：多線染色體（polytenechromosome）燈刷染色體（lampbrushchromosome）

四、巨大染色體

giantchromosome

44Endomitosis（核內(nèi)有絲分裂）Chromocenter（染色中心）Bands（帶）andinterbands（間帶）LuxurygenesHouse-keepinggenesPolytenechromosomes

多線染色體15%DNA85%DNA45帶和間帶(Bandsandinterbands):85%DNA15%DNAinterbands46Puffsinplolytenechromosome:GeneactivityPuffs（脹泡）:transcriptionallyactivechromatin47（二）燈刷染色體

Lampbrushchromosomes最早發(fā)現(xiàn)于魚類、兩棲類和爬行類卵母細(xì)胞減數(shù)分裂的雙線期。由于染色體主軸兩側(cè)有側(cè)環(huán)，狀如燈刷，故名燈刷染色體IngrowingamphibianoocyteStayinmeiosisI48StructureFunctions:TranscriptintoRNA,storage大部分DNA以染色粒形式存在，沒有轉(zhuǎn)錄活性，而側(cè)環(huán)是RNA活躍轉(zhuǎn)錄的區(qū)域。配對的燈刷染色體49Section5nucleolus（核仁）---notsurroundedbyamembrane

50Nucleolarultrastructure（核仁超微結(jié)構(gòu)）Functionsofthenucleolus（核仁功能）Nucleoluscycle（核仁周期）Nuclearbodies(核體)Section5TheNucleolus

第五節(jié)核仁51一、Nucleolarultrastructu

核仁的超微結(jié)構(gòu)consistsofthreemorphologicallydistinctregions:fibrillarcenters(FC)--纖維中心densefibrillarcomponent(DFC)--致密纖維成分granularcomponent(GC)--顆粒成分Summaryofnucleolarultrastructure521.The

fibrillarcenters(FC):Oneormore(一個或幾個)circularareas(圓形結(jié)構(gòu))pale(低電子密度、淺染)ContainsrDNA、rRNA聚合酶染色體NOR在間期核的副本532.densefibrillarcomponent(DFC):ElectrondensefilamentsaroundFC(電子密度最高，包繞FC)ContainsnascentrRNAtranscripts543.granularcomponent(GC):containsribosomalprecursoratvariousstagesofassembly.

不同階段核糖體亞單位前體顆?？杀坏鞍酌负蚏Nase消化GC是核仁的主要結(jié)構(gòu)GC組分?jǐn)?shù)量的差異決定核仁的大小55

ultrastructureoftheNucleolusFC:纖維中心DFC:致密纖維成分GC:顆粒成分56Mammaliannucleolitypicallycontainseveralfibrillarcenters(FC),eachencircledbyalayerofdensefibrillarcomponent(DFC),whichinturnissurroundedbythegranularcomponent(GC).57二、Functionsofthenucleolus

--ribosomalbiogenensis

核仁的功能——核糖體的生物發(fā)生Itsmainfunctionistranscription(轉(zhuǎn)錄)andprocessing(加工)ofribosomalRNAandassembly(組裝)ofribosomalsubunits.pre-rRNAsynthesisProcessAssemblyFC.DFCDFC.GCGC58Summary組成功能FCrDNA儲存rRNA基因DFCrRNA儲存、加工rRNA初級轉(zhuǎn)錄本GCRNP組裝、儲存ribosome亞基59rRNAgenesaretandemly(串聯(lián))arrayedChristmas-Liketreewhentranscribed游離端(5‘端)首先形成RNP顆粒(一)rRNA基因的轉(zhuǎn)錄TranscriptionofribosomalRNA60

RibosomalRNAGenesrRNArRNAgene(rDNA)聚合酶移動及RNA鏈生長的方向61pre-rRNAtranscriptionunits轉(zhuǎn)錄單位ShowingtworRNAgenesseperatedbynontranscribedspacerDNA.兩個rRNA基因被分隔62

aclusteroftandemlyrepeatedrRNAgenes

primaryRNAtranscript,knownas45SrRNA.串聯(lián)重復(fù)排列增加了啟動子的局部濃度RNA聚合酶Ⅰ能連續(xù)運(yùn)作63(二)rRNA前體的加工

45SRNA5.8SrRNA,18SrRNA,and28SrRNA.

ProcessingofribosomalRNA64Assemblyofribosomalsubunits(三)核糖體亞單位的