《染色体畸变数目改变.ppt》由会员分享，可在线阅读，更多相关《染色体畸变数目改变.ppt（52页珍藏版）》请在taowenge.com淘文阁网|工程机械CAD图纸|机械工程制图|CAD装配图下载|SolidWorks_CaTia_CAD_UG_PROE_设计图分享下载上搜索。
1、Alterationsinsexchromosomenumber（教材上册教材上册p142）Turner Syndrome Turner Syndrome(45,X)1 in 2500 liveborn femalesCharacteristicsCharacteristicso oShort stature&Short stature&Webbed neckWebbed necko oOvarian Ovarian dysgenesis,dysgenesis,primary primary amenorrhea,amenorrhea,infertilityinfertilityo oAbse
2、nce Absence of of secondary secondary sex sex characteristicscharacteristicso oUnderdeveloped Underdeveloped breasts;breasts;wide nippleswide nipples性性性性腺腺腺腺发发发发育育育育不不不不全全全全综综综综合合合合症症症症身身材材矮矮，蹼蹼颈颈，肘肘外外翻翻，原原发发性性闭闭经经，生生殖殖器器幼幼稚稚，索索状状性性腺腺（结缔组织，无卵泡）。成因：早期卵裂过程中染色体不分离。（结缔组织，无卵泡）。成因：早期卵裂过程中染色体不分离。多数有生育能力，少数
3、卵巢功能异常，多数有生育能力，少数卵巢功能异常，2/32/3伴有轻度智力低下，并有患精神病的倾向。伴有轻度智力低下，并有患精神病的倾向。Two of the three X chromosomes are inactivated.1 in 800 malesoTall with disproportionately long arms/legsKlinefelter syndrome(47,XXY)（克氏综合症）（克氏综合症）1 in 100 mentally retarded males1 in 10 infertile malesoPoorly developed secondary se
4、x characteristicsoTesticular dysgenesisAlterationsinsexchromosomenumber先先先先天天天天性性性性睾睾睾睾丸丸丸丸发发发发育育育育不不不不全全全全综综综综合合合合征征征征女女性性体体态态，有有女女性性化化乳乳房房，胡胡须须少少，皮皮肤肤较较嫩嫩；睾睾丸丸小小而而硬硬，无无精精子子，但睾丸间质细胞不萎缩；智力低下。但睾丸间质细胞不萎缩；智力低下。1 in 750 1500 malesoTall statureXYY syndrome(47,XYY)1 in 30 male prison populations oPredispo
5、sition to violent,criminal behavior180 cm:1/200190 cm:1/30200 cm:1/10AlterationsinsexchromosomenumberAlterationsinautosomenumber（教材下册教材下册P41）Down Syndrome Down Syndrome(trisomy 21 syndrome)病因：比正常人病因：比正常人多了一条多了一条2121号常号常染色体染色体唐唐氏氏综综合合症症：智智力力低低下下，身身体体发发育育缓缓慢慢。常常表表现现为为特特殊殊的的面面容容,较较敏敏感感和和快快乐乐,寿命短。寿命短。Ch
6、aracteristicsCharacteristicsoGrowth retardationoVarying degrees of mental retardationoFlattened face oUpward slanting of the eyes with epicanthal folds1 in 600 800 newbornsDown Syndrome Down Syndrome(trisomy 21 syndrome)皮肤折痕皮肤折痕DownSyndromeandMaternalAgeAsmaternalageincreases,therisk of having a bab
7、y withDownsyndromeincreasesAtage20lessthan1in1000birthsresultsindownsyndromeAfterage40,greaterthan1in100 births results in Downsyndrome如果如果经适当经适当教育，唐氏症患者依然可以有很好的表現教育，唐氏症患者依然可以有很好的表現Trisomy18:EdwardsSyndrome(47,+18)smallatbirth,veryslowgrowing,mentalretardation,malformedfeet,heartmalformations.Forunk
8、nownreasons,80%ofliveborntrisomy18babiesarefemale.Edwards Syndrome Edwards Syndrome(trisomy 18 syndrome)Trisomy13:PatauSyndrome(47,+13)Facial malformations,eyedefects,extrafingers or toes,feetwith protruding heels,malformations of thebrain,nervoussystem,heartdefectsFrequenciesofTrisomiesinSpontaneou
9、sAbortionsSome Chromosomes arerarelyseenastrisomiesinabortuses(1,5,11,17,19)Otherchromosomesoccurfrequentlyastrisomies(16)The reasons for thesedifferencesarenotclear.Aneuploidy:AlterationsinChromosomeNumberAlterationsinchromosomenumber can cause polyploidyofcells.Theoccurrenceofanentireextrasetofchr
10、omosomesproduces triploid cells.Thiscan be caused by a nuclearduplicationwithnocelldivision in meiosis,or morecommonly by fertilization ofoneovumbytwosperm.TriploidyTriploidindividualsare born infrequently,andsurviveforonlyashorttimeIn this circumstance,allofthepropergeneticmaterialispresent,onlythe
11、rearethree copies of eachchromosomeratherthantwo.CausesofGeneticAbnormalitiesUnequal crossing over can cause changes in gene regions with similar or repeated sequenceNon-disjunction(不不分分开开)can cause changes in chromosome number(aneuploidy，非整倍体非整倍体)Meiosis Nondisjunction Nondisjunctioncanproducediffe
12、rentoutcomesdependingonwhether it occursin meiosis 1 ormeiosis2Mitotic Nondisjunction Nondisjunctionduringmitosiscanproducemosaics,individualswithtwotypesofchromosomearrangements.Chromosomal Lagging Chromosomallaggingcanresultinthelossofone(ormore)chromosomes,eitherinmeiosisormitosis.Alterations in
13、Chromosome Number in plant 染色体数目的变异整整倍倍体体变变异异二倍体（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）非非整整倍倍体体变变异异单体(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
14、):（2n+2）双三体(doubletrisomic):（2n+1+1）Chromosome complement:染色体组（下册P26）DiploidyDiploidyisthestateofhavingtwocopiesofeverysinglegene-likepairsofshoes.Humans,andmanyoftheorganismswithwhichwearefamiliar(flies,zebras,potatoes),arediploid.Wehavetwocopiesofeverygeneinourbodies.Formanygenes,thesecopiesareide
15、nticalmatches(theyarehomozygous).Forothers,therearesubtledifferencesbetweenthetwocopies(theyareheterozygous).DiploidyNotallorganismsarediploidasadults,somearehaploid.Forsexualreproductiontooccur,theremustbebothadiploidandahaploidphaseofthelifecycle.Polyploidy(多倍体多倍体)and Speciation(物种形成物种形成)(1)Triplo
16、idindividualsareoftensterile(不育的).Since the chromosomesare unableto pair duringmeiosis,unequalsegregationoftenresults(2)Tetraploidindividualsarelesslikelytobesterile.(3)Inplants,polyploidconditionsarenotuncommon,andmaybethesourceofmanynewspecies.Meiosis in a Triploid 二体性Autopolyploidy（同源同源多倍体）多倍体）an
17、d Allopolyploidy（异源异源多倍体）多倍体）Polyploidplantscanresultfromdoublingofchromosomesinaspecies(autopolyploidy)orfromdoublingchromosomesnumberafterhybridization(allopolyploidy).Hybridizationand Polyploidy(1)ThehybridF1issterile（不不育育的的）,sincethetwosets of chromosomes cannotpairduringmeiosis.(2)Ifthechromoso
18、menumberisdoubled,thechromosomes each have ahomologwithwhichtopair,andthepolyploidisfertile（可育的可育的）.(萝卜萝卜甘蓝甘蓝)F1未减数配子融合未减数配子融合普通小麦普通小麦(Triticum aestivum)的起源的起源三倍体无子西瓜的培育过程三倍体无子西瓜的培育过程父本父本母本母本授粉授粉四倍体四倍体二倍体二倍体有子西瓜有子西瓜种下去种下去三倍体三倍体植株植株花粉刺激花粉刺激（提供生长素）（提供生长素）普通西瓜植株普通西瓜植株无子西瓜无子西瓜八倍体小黑麦的人工合成与应用八倍体小黑麦的人工合成与应
19、用(鲍文奎等鲍文奎等)秋水仙素处理萌发的种子或幼苗秋水仙素处理萌发的种子或幼苗四倍体小黑麦（不育）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（耐贫瘠的土壤和寒冷的气候，面粉白，蛋白质含量高，产量高)二倍体黑麦二倍体黑麦六倍体普通小麦六倍体普通小麦八倍体小黑麦（八倍体小黑麦（8n）同源同源多倍体的特征(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
20、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。(1)异源多倍体是广泛存在的。被子植物纲中有30-35是异源多倍体；禾本科植物有70是异源多倍体，如：小麦、燕麦、甘蔗等；其它农作物；烟草、甘蓝型油菜、棉花等也是异源多倍体。(2)自然界中能正常繁殖的异源多倍体物种几乎都是偶倍数。因为细胞内的染色体组成对存在，同源染色体能正常配对形成二价体，并分配到配子中去，因而其遗传表现与二倍体相似。异源异源多倍体存在的广泛性多倍体存在的广泛性课堂讨论：1染色体结构变异修复机制；人类染色体畸变分析与遗传病
21、？2染色体数目变异对动、植物个体的影响的异同。作业与思考题：作业与思考题：1.本章的基本概念和名词术语。2.阅读全书或其它参考资料，思考造成染色体结构变异的机制（或原因）有哪些？3.选择教材及主要参考书上的部分计算题和综合分析题。4结合遗传学实验，总结诱变的细胞学特征。5主要染色体畸变类型的遗传分析。6缺失、重复和倒位在减数第一分裂前期染色体形态上所表 现 的 相 拟 性，镜 检 时 怎 样 区 别 它 们？7微缺失和基因突变有类似的表现型，怎样对其进行正确的判定？8倒位杂合体和易位杂合体都能产生不育配子，为什么称半不育是易位杂合体的突出特点？9缺失、倒位和易位都能影响到重组率，在影响的机制上它们之间有何不同？10比较染色体基组与染色体组型各自的含义。11同源多倍体和异源多倍体是怎样形成的？12超倍体有哪些类型？它们各自的遗传特点和实践意义如何？13亚倍体有哪些类型？它们各自的遗传特点和实践意义如何？