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1、Part2. GenomeAnatomiesChapter7.EukaryoticnucleargenomesChapter8.GenomesofprokaryotesandeukaryoticorganellesChapter9.virusgenomesandmobilegeneticelementsChapter7.Eukaryoticnucleargenomes7.1.NucleargenomesarecontainedinchromosomesChromosomenumberisunrel
2、atedtobiologicalfeaturesoftheorganism.Yeast(16),fruitfly(4).Norischromosomenumberlinkedtogenomesize(somesalamandershavegenomes30timesbiggerthanhumanbutabouthalfthenumberofchromosomes)Howdochromosomenumberchange?Anunexpectedway.Saccharomycescerevisiae(
3、buddingyeast,brewer’syeast,distiller’syeastorwineyeast,)Schizosaccharomycespombe(fissionyeast)7.1.1PackagingofDNAintochromosomeNucleosomeandhigherlevelpackageSomethingnewTilgner,H.etal.Nucleosomepositioningasadeterminantofexonrecognition.NatureStruct.
4、Mol.Biol.16,996–1001(2009)Schwartz,S.etal.Chromatinorganizationmarksexon–intronstructure.NatureStruct.Mol.Biol.16,990–995(2009)Andersson,R.etal.Nucleosomesarewellpositionedinexonsandcarrycharacteristichistonemodifications.GenomeRes.19,1732-41(2009).Wh
5、enchromatinmeetssplicing.NatureStruct.Mol.Biol.16,902-903(2009)Chromatin:Apeakforexons.NatureRev.Genet.10,664-665(October2009)SomethingNewThelong-standingviewofchromosomepackagingisthat10-nmbeads-on-astringchromatinfibresfoldintohigherorder30-nmfibres
6、,whichfurthertwistandcoiltoformhighlycondensedchromosomes.Nishinoetal(2012)demonstratesthatregular30-nmfibresareabsentfromhumanmitoticchromosomes.Theemergingviewisthatchromosome-levelcondensationcanbeachievedthroughpackagingof10-nmfibresinafractalmann
7、er.1.HansenJC:Humanmitoticchromosomestructure:whathappenedtothe30-nmfibre?EMBOJ2012,31:1621-1623.2.NishinoY,etal.:Humanmitoticchromosomesconsistpredominantlyofirregularlyfoldednucleosomefibreswithouta30-nmchromatinstructure.EMBOJ2012,31:1644-1653.Thet
8、ypicalappearanceofametaphasechromosomeUntypicalchromosomesMinichromosomesandmacrochromosomesBchromosomesHolocentricchromosomes，inCaenorhabditiselegansHeterochromatin:nottotallysilenced.Arabidopsiscentromeresspan0.9-1.2MbofDNAandeachoneismadeup
