染色体畸变-数目改变课件

Alterationsinsexchromosomenumber（教材上册p142）7.2染色体畸变-数目改变TurnerSyndrome(45,X)1in2500livebornfemalesCharacteristicsShortstature&WebbedneckOvariandysgenesis,primaryamenorrhea,infertilityAbsenceofsecondarysexcharacteristicsUnderdevelopedbreasts;widenipples性腺发育不全综合症7.2染色体畸变-数目改变身材矮，蹼颈，肘外翻，原发性闭经，生殖器幼稚，索状性腺（结缔组织，无卵泡）。成因：早期卵裂过程中染色体不分离。7.2染色体畸变-数目改变7.2染色体畸变-数目改变多数有生育能力，少数卵巢功能异常，2/3伴有轻度智力低下，并有患精神病的倾向。TwoofthethreeXchromosomesareinactivated.7.2染色体畸变-数目改变1in800malesTallwithdisproportionatelylongarms/legsKlinefeltersyndrome(47,XXY)（克氏综合症）1in100mentallyretardedmales1in10infertilemalesPoorlydevelopedsecondarysexcharacteristicsTesticulardysgenesisAlterationsinsexchromosomenumber先天性睾丸发育不全综合征7.2染色体畸变-数目改变女性体态，有女性化乳房，胡须少，皮肤较嫩；睾丸小而硬，无精子，但睾丸间质细胞不萎缩；智力低下。7.2染色体畸变-数目改变7.2染色体畸变-数目改变7.2染色体畸变-数目改变1in750~1500malesTallstatureXYYsyndrome(47,XYY)1

in30maleprisonpopulationsPredispositiontoviolent,criminalbehavior＞180cm:1/200＞190cm:1/30＞200cm:1/10Alterationsinsexchromosomenumber7.2染色体畸变-数目改变7.2染色体畸变-数目改变Alterationsinautosomenumber（教材下册P41）7.2染色体畸变-数目改变DownSyndrome(trisomy21syndrome)病因：比正常人多了一条21号常染色体唐氏综合症：智力低下，身体发育缓慢。常表现为特殊的面容,较敏感和快乐,寿命短。7.2染色体畸变-数目改变7.2染色体畸变-数目改变CharacteristicsGrowthretardationVaryingdegreesofmentalretardationFlattenedfaceUpwardslantingoftheeyeswithepicanthalfolds1in600~800newbornsDownSyndrome(trisomy21syndrome)7.2染色体畸变-数目改变皮肤折痕7.2染色体畸变-数目改变7.2染色体畸变-数目改变DownSyndromeandMaternalAgeAsmaternalageincreases,theriskofhavingababywithDownsyndromeincreasesAtage20lessthan1in1000birthsresultsindownsyndromeAfterage40,greaterthan1in100birthsresultsinDownsyndrome7.2染色体畸变-数目改变如果经适当教育，唐氏症患者依然可以有很好的表現7.2染色体畸变-数目改变7.2染色体畸变-数目改变7.2染色体畸变-数目改变Trisomy18:Edward’sSyndrome(47,+18)smallatbirth,veryslowgrowing,mentalretardation,malformedfeet,heartmalformations.Forunknownreasons,80%ofliveborntrisomy18babiesarefemale.7.2染色体畸变-数目改变EdwardsSyndrome(trisomy18syndrome)7.2染色体畸变-数目改变7.2染色体畸变-数目改变7.2染色体畸变-数目改变Trisomy13:PatauSyndrome(47,+13)Facialmalformations,eyedefects,extrafingersortoes,feetwithprotrudingheels,malformationsofthebrain,nervoussystem,heartdefects7.2染色体畸变-数目改变7.2染色体畸变-数目改变FrequenciesofTrisomiesinSpontaneousAbortionsSomeChromosomesarerarelyseenastrisomiesinabortuses(1,5,11,17,19)Otherchromosomesoccurfrequentlyastrisomies(16)Thereasonsforthesedifferencesarenotclear.7.2染色体畸变-数目改变Aneuploidy:AlterationsinChromosomeNumberAlterationsinchromosomenumbercancausepolyploidyofcells.Theoccurrenceofanentireextrasetofchromosomesproducestriploidcells.Thiscanbecausedbyanuclearduplicationwithnocelldivisioninmeiosis,ormorecommonlybyfertilizationofoneovumbytwosperm.7.2染色体畸变-数目改变TriploidyTriploidindividualsareborninfrequently,andsurviveforonlyashorttimeInthiscircumstance,allofthepropergeneticmaterialispresent,onlytherearethreecopiesofeachchromosomeratherthantwo.7.2染色体畸变-数目改变CausesofGeneticAbnormalitiesUnequalcrossingovercancausechangesingeneregionswithsimilarorrepeatedsequenceNon-disjunction(不分开)cancausechangesinchromosomenumber(aneuploidy，非整倍体)7.2染色体畸变-数目改变MeiosisNondisjunction

Nondisjunctioncanproducedifferentoutcomesdependingonwhetheritoccursinmeiosis1ormeiosis27.2染色体畸变-数目改变MitoticNondisjunction

Nondisjunctionduringmitosiscanproducemosaics,individualswithtwotypesofchromosomearrangements.7.2染色体畸变-数目改变ChromosomalLaggingChromosomallaggingcanresultinthelossofone(ormore)chromosomes,eitherinmeiosisormitosis.7.2染色体畸变-数目改变AlterationsinChromosomeNumberinplant

染色体数目的变异整倍体变异二倍体（2n，AA）

同源三倍体（3n，AAA）

同源多倍体（autoploid）同源四倍体（4n，AAAA）多倍体

异源三倍体（3n，ABC）

异源多倍体（allopolyploid）异源四倍体（4n，AABB）

异源六倍体（6n，BBCC）单倍体（haploid）（n）非整倍体变异单体(monosomic):（体细胞内染色体数目=2n-1缺体(nullisomic):（2n-2）双单体(doublemonosomic):（2n-1-1）三体(trisomic):（2n+1）四体(tetrasomic):（2n+2）双三体(doubletrisomic):（2n+1+1）Chromosomecomplement:染色体组（下册P26）7.2染色体畸变-数目改变DiploidyDiploidyisthestateofhavingtwocopiesofeverysinglegene-likepairsofshoes.Humans,andmanyoftheorganismswithwhichwearefamiliar(flies,zebras,potatoes),arediploid.Wehavetwocopiesofeverygeneinourbodies.Formanygenes,thesecopiesareidenticalmatches(theyarehomozygous).Forothers,therearesubtledifferencesbetweenthetwocopies(theyareheterozygous).7.2染色体畸变-数目改变DiploidyNotallorganismsarediploidasadults,somearehaploid.Forsexualreproductiontooccur,theremustbebothadiploidandahaploidphaseofthelifecycle.

7.2染色体畸变-数目改变Polyploidy(多倍体)andSpeciation(物种形成)(1)Triploidindividualsareoftensterile(不育的).Sincethechromosomesareunabletopairduringmeiosis,unequalsegregationoftenresults(2)Tetraploidindividualsarelesslikelytobesterile.(3)Inplants,polyploidconditionsarenotuncommon,andmaybethesourceofmanynewspecies..7.2染色体畸变-数目改变MeiosisinaTriploid二体性7.2染色体畸变-数目改变Autopolyploidy（同源多倍体）

andAllopolyploidy（异源多倍体）Polyploidplantscanresultfromdoublingofchromosomesinaspecies(autopolyploidy)orfromdoublingchromosomesnumberafterhybridization(allopolyploidy).7.2染色体畸变-数目改变HybridizationandPolyploidy(1)ThehybridF1issterile（不育的）,sincethetwosetsofchromosomescannotpairduringmeiosis.(2)Ifthechromosomenumberisdoubled,thechromosomeseachhaveahomologwithwhichtopair,andthepolyploidisfertile（可育的）.7.2染色体畸变-数目改变(萝卜×甘蓝)F1未减数配子融合7.2染色体畸变-数目改变普通小麦(Triticumaestivum)的起源7.2染色体畸变-数目改变三倍体无子西瓜的培育过程7.2染色体畸变-数目改变父本母本授粉四倍体二倍体有子西瓜7.2染色体畸变-数目改变种下去三倍体植株花粉刺激（提供生长素）普通西瓜植株无子西瓜7.2染色体畸变-数目改变7.2染色体畸变-数目改变八倍体小黑麦的人工合成与应用(鲍文奎等)秋水仙素处理萌发的种子或幼苗四倍体小黑麦（不育）（耐贫瘠的土壤和寒冷的气候，面粉白，蛋白质含量高，产量高)二倍体黑麦六倍体普通小麦八倍体小黑麦（8n）7.2染色体畸变-数目改变同源多倍体的特征(1)形态特征：表现大型性随染色体组数的增加，同源多倍体的细胞、细胞核、营养器官、生殖器官等多数有增大的趋势，表现为叶片肥厚、宽大、长，茎杆粗壮，花、花粉粒、果实、种子、气孔等器官组织较大，产量较二倍体高。(2)生理生化代谢的改变：表现基因的剂量效应同源多倍体的生化反应与代谢活动加强，许多性状的表现更强。如：大麦同源四倍体籽粒蛋白质含量比二倍体原种增加10-12％；玉米同源四倍体籽粒胡萝卜素含量比二倍体原种增加43％。7.2染色体畸变-