人类染色体的正常核型

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1、一、染色质chromatin二、染色体chromosome三、人类染色体的正常核型thenormalhumankaryotype四、染色体的多态性chromosomepolymorphism第二节遗传的细胞基础CellularBasisofInheritance(一)染色质的分子结构chromatinstructure(二)常染色质和异染色质euchromatinandheterochromatin(三)性染色质(sexchromatin)XchromatinYchromatinChromatin一、染色质（1）Chromatin

2、一、染色质（2）1Chemicalcomponentsofchromatin:DNA、protein、alittleofRNA2Higherlevelsofchromatinstructure:FourlevelsofDNApackingChromatin一、染色质（3）30nmchromatinfiberofpackednucleosomes.SectionofchromosomeinanextendedformChromatid“Beads-on-a-string”formofchromatin.Higherlevelsofc

3、hromatinstructure:FourlevelsofDNApackingCellHistonesDNAChromatin一、染色质（4）核小体/nucleosomeChromatin一、染色质（5）DNAnucleosomeChromatid×7×6×40×5×8400Chromatin一、染色质（6）30nmchromatinfiberofpackednucleosomes.Sectionofchromosomeinanextendedform染色质chromatinInterphase。染色体chromosomeM

4、phaseChromatin一、染色质（7）常染色质(heterochromatin)和异染色质(euchromatin)euchromatin:active,lesscompact。Heteromatin:repressed,concentrated。heterochromatineuchromatinChromatin一、染色质（8）1949，BarrBarrbodyXbodyChromatin一、染色质（9）X染色质(Xchromatin)：female,interphase,1μmbody,heterochromatin

5、Chromatin一、染色质（10）1961年，LyonX染色体失活假说(Lyonhypothesis)：①onlyoneofthetwoX-chromosomesisgeneticallyactiveinfemalecells.TheinactiveXchromosomeissilencedbypackagingintotranscriptionallyinactiveheterochromatin②ThechoiceofwhichXchromosomewillbeinactivatedisrandominplacentalma

6、mmalssuchasmiceandhumans,butonceanXchromosomeisinactivateditwillremaininactivethroughoutthelifetimeofthecell.Chromatin一、染色质（11）Dosagecompensationeffect剂量补偿效应Y染色质(Ychromatin)：maleinterphase0.3μmbody,Q-brightregionofYchromosomeChromatin一、染色质（12）structure;:短臂p长臂q着丝粒centr

7、omere主缢痕primaryconstriction端粒telomere次缢痕secondaryconstriction随体satellite二、染色体(1)ChromosomeStructure,typeandnumberType二、染色体(2)ChromosomeMetacentricchromosome:1/2-5/8Submetacentricchromosome:5/8–7/8Acrocentricchromosome:7/8-telomere(一)非显带核型Karyotypewithoutband核型karyotyp

8、e核型分析karyotypeanalysis三、人类染色体的正常核型（1）ThenormalhumankaryotypetypemethodsGbandingtrypsin,GiemsaQbandingquinacrinemustardQMRban