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1、Alterationsinsexchromosomenumber教材上册p142Turner Syndrome (45, X)Turner Syndrome (45, X)1 in 2500 liveborn femalesCharacteristicsCharacteristicso oShort stature & Webbed neckShort stature & Webbed necko oOvarian Ovarian dysgenesis, dysgenesis, primary primary amenorrhea, infertilityamenorrhea, inferti
2、lityo oAbsence 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育育育育不不不不全全全全综综合合合合症症症症身身体体矮矮，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别。结缔组织，无卵泡。成因：早期卵裂过程中染色体不分别。多数有生育
3、才干，少数卵巢功能异常，多数有生育才干，少数卵巢功能异常，2/32/3伴有伴有轻度智力低下，并有患精神病的度智力低下，并有患精神病的倾向。向。Two of the three X chromosomes are inactivated.1 in 800 malesoTall with disproportionately long arms/legsKlinefelter syndrome (47, XXY) 克氏克氏综综合症合症 1 in 100 mentally retarded males1 in 10 infertile malesoPoorly developed secondary
4、 sex characteristicsoTesticular dysgenesisAlterationsinsexchromosomenumber先先先先天天天天性性性性睾睾睾睾丸丸丸丸发发育育育育不不不不全全全全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 oPredisp
5、osition to violent, criminal behavior180 cm: 1/200190 cm: 1/30200 cm: 1/10AlterationsinsexchromosomenumberAlterationsinautosomenumber教材下册P41Down Syndrome (trisomy 21 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氏唐氏综合症：智合症：智力低下，身体力低下，身体发育育缓慢。常表慢。常表现为特殊的面容特殊的面容, ,较敏
6、感和高敏感和高兴, ,寿命短。寿命短。CharacteristicsCharacteristicsoGrowth retardationoVarying degrees of mental retardationoFlattened face oUpward slanting of the eyes with epicanthal folds1 in 600 800 newbornsDown Syndrome (trisomy 21 syndrome)Down Syndrome (trisomy 21 syndrome)皮肤折痕皮肤折痕DownSyndromeandMaternalAgeAsm
7、aternalageincreases,therisk of having a baby withDownsyndromeincreasesAtage20lessthan1in1000birthsresultsindownsyndromeAfterage40,greaterthan1in100 births results in Downsyndrome假设经适当教育，唐氏症患者依然可以有很好的表現假设经适当教育，唐氏症患者依然可以有很好的表現Trisomy18:EdwardsSyndrome(47,+18)smallatbirth,veryslowgrowing,mentalretardat
8、ion,malformedfeet,heartmalformations.Forunknownreasons,80%ofliveborntrisomy18babiesarefemale.Edwards Syndrome (trisomy 18 syndrome)Edwards Syndrome (trisomy 18 syndrome)Trisomy13:PatauSyndrome(47,+13)Facial malformations,eyedefects,extrafingers or toes, feetwith protruding heels,malformations of the
9、brain,nervoussystem,heartdefectsFrequenciesofTrisomiesinSpontaneousAbortionsSome Chromosomes arerarelyseenastrisomiesinabortuses (1, 5, 11, 17,19)Otherchromosomesoccurfrequentlyastrisomies(16)The reasons for thesedifferencesarenotclear.Aneuploidy:AlterationsinChromosomeNumberAlterationsinchromosomen
10、umber can cause polyploidyofcells.Theoccurrenceofanentireextrasetofchromosomesproduces triploid cells. Thiscan be caused by a nuclearduplicationwithnocelldivision in meiosis, or morecommonly by fertilization ofoneovumbytwosperm.TriploidyTriploidindividualsare born infrequently,andsurviveforonlyashor
11、ttimeIn this circumstance,allofthepropergeneticmaterialispresent,onlytherearethree 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 numbe
12、r (aneuploidy，非整倍体，非整倍体)Meiosis Nondisjunction Nondisjunctioncanproducedifferentoutcomesdependingonwhether it occursin meiosis 1 ormeiosis2Mitotic Nondisjunction Nondisjunctionduringmitosiscanproducemosaics,individualswithtwotypesofchromosomearrangements.Chromosomal Lagging Chromosomallaggingcanresu
13、ltinthelossofone(ormore)chromosomes,eitherinmeiosisormitosis.Alterations in 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
14、双单体(doublemonosomic):2n-1-1三体(trisomic):2n+1四体(tetrasomic):2n+2双三体(doubletrisomic):2n+1+1Chromosome complement: 染色体组下册染色体组下册P26DiploidyDiploidy is the state of having two copies of every single gene-like pairs of shoes. Humans, and many of the organisms with which we are familiar (flies, zebras, pot
15、atoes), are diploid. We have two copies of every gene in our bodies. For many genes, these copies are identical matches (they are homozygous).For others, there are subtle differences between the two copies (they are heterozygous).DiploidyNotallorganismsarediploidasadults,somearehaploid.Forsexualrepr
16、oductiontooccur,theremustbebothadiploidandahaploidphaseofthelifecycle.Polyploidy (多倍体多倍体) and Speciation (物种构成物种构成)(1)Triploidindividualsareoftensterile(不育的).Since the chromosomesare unableto pair duringmeiosis,unequalsegregationoftenresults(2)Tetraploidindividualsarelesslikelytobesterile.(3)Inplant
17、s,polyploidconditionsarenotuncommon,andmaybethesourceofmanynewspecies.Meiosis in a Triploid 二体性Autopolyploidy同源多倍体同源多倍体 and Allopolyploidy 异源多倍体异源多倍体Polyploidplantscanresultfromdoublingofchromosomesinaspecies(autopolyploidy)orfromdoublingchromosomesnumberafterhybridization(allopolyploidy).Hybridizat
18、ionand Polyploidy(1)ThehybridF1issterile不育的,sincethetwosetsof chromosomescannotpairduringmeiosis.(2)Ifthechromosomenumberisdoubled,thechromosomes each have ahomologwithwhichtopair,andthepolyploidisfertile可育的.(萝卜卜甘甘蓝) F1未减数配子交融未减数配子交融普通小麦普通小麦(Triticum aestivum)的来源的来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
19、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提供生长素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运用八倍体小黑麦的人工合成与运用(鲍文奎等鲍文奎等)秋水仙素秋水仙素处置萌生的种子或幼苗置萌生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冰冷的气候，面粉白，蛋白质含量高，产量高耐贫瘠的土壤和冰冷的气候，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同源多倍体的特征同源多倍体的特征(1)形状特征：表现大型性 随染色体组数的添加，同源多倍体的细胞、细胞
20、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)生理生化代谢的改动：表现基因的剂量效应 同源多倍体的生化反响与代谢活动加强，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添加10-12；玉米同源四倍体籽粒胡萝卜素含量比二倍体原种添加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)自然界中能正常繁衍的异源多倍体物种几乎都是偶倍数。由于细胞内的染色体
21、组成对存在，同源染色体能正常配对构成二价体，并分配到配子中去，因此其遗传表现与二倍体类似。异源多倍体存在的广泛性异源多倍体存在的广泛性课堂讨论：1染色体构造变异修复机制；人类染色体畸变分析与遗传病？2染色体数目变异对动、植物个体的影响的异同。作业与思索题：1. 本章的根本概念和名词术语。2. 阅读全书或其它参考资料，思索呵斥染色体构造变异的机制或缘由有哪些？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、反复和倒位在减数第一分裂前期染色体形状上所表 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，怎样对其进展正确的断定？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构成的？12超倍体有哪些类型？它们各自的遗传特点和实际意义如何？13亚倍体有哪些类型？它们各自的遗传特点和实际意义如何？
