7ChromosomeMutationVariationinNumberandArrangement.ppt
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1、Xunchao Xiang Southwest University of Science and Technology,Chapter 7 Chromosome Mutations: Variation in Number and Arrangement,7.1 Variation in Chromosome Number: An Overview 7.2 Nonjunction: The Origin of Aneuploidy 7.3 Monosomy 7.4 Trisomy 7.5 Polyploidy and Its Origins 7.6 Variation in Chromoso
2、me Structure and Arrangement: An Overview 7.7 Deletions 7.8 Duplications 7.9 Inversions 7.10 Translocations,Xunchao Xiang Southwest University of Science and Technology,7.1 Variation in Chromosome Number: An Overview,Genome: the total set of genes contained in a haploid of the species constitutes th
3、e genome. The all chromosomal number of a gamete produced from diploid is designated as basic chromosome number 染色体基数, and make up a single complete set (x) . Monoploid (x)一倍体: individual, which has only one set of chromosomes. Haploid(单倍体): individual only with gametic chromosomes. Its all chromoso
4、mal number is indicated as n.,Xunchao Xiang Southwest University of Science and Technology,1. 单倍体的产生,(1)自然产生:由单性生殖产生 未受精的雌、雄配子,甚至助细胞、反细胞等直接发育形成单倍体胚。 部分动物,如膜翅目昆虫(蜂、蚊)和某些同翅目昆虫(白蚁)的雄性个体都是孤雌生殖形成的自然单倍体。 (2) 人工获得单倍体 花药培养:花药离体培养诱导配子体(花粉或子房)发育形成单倍体植株 这是应用最为广泛、成功的人工方法 种间或属间远缘杂交 栽培大麦(Hordeum vudare, 2n=2x=14)
5、与野生球茎大麦(H. bulbosus, 2n=2x=14)杂种胚发育过程中,两物种染色体的行为不协调可导致球茎大麦的染色体逐渐丢失(称为染色体消减现象),可获得大麦的单倍体植株,Xunchao Xiang Southwest University of Science and Technology,花药培养获得单倍体,染色体消减获得单倍体大麦,Xunchao Xiang Southwest University of Science and Technology,2. 单倍体在遗传育种研究的应用,(1)提高育种的选择效率、加速育种进程 基因成单,加倍,纯合体 (2)作为良好的遗传研究材料 基
6、因成单,每个基因都发挥作用 (3)用以分析染色体组间同源关系 部分同源关系,Xunchao Xiang Southwest University of Science and Technology,7.1 Variation in Chromosome Number: An Overview,Euploid(整倍体): an individual that has complete sets of chromosomes present. Aneuploid (非整倍体): an individual gains or loses one or more chromosomes, but no
7、t a complete set. Polyploid (多倍体): an individual with more than two complete sets chromosomes present.,Xunchao Xiang Southwest University of Science and Technology,7.1 Variation in Chromosome Number: An Overview,Terminology for Variation in Chromosome Numbers Term Explanation Disomic (normal) 2n Ane
8、uploid 2nx chromosomes Monosomic 2n1 Double Monosomic 2n11 Nullisomic 2n2 Trisomic 2n1 Double Trisomic 2n11 Tetrasomic, pentasomic, etc. 2n 2, 2n 3, etc. Euploid Multiples of n Diploid 2n Polyploid 3n,4n,5n,Xunchao Xiang Southwest University of Science and Technology,Polyploidy,Term Explanation Trip
9、loid(三倍体) 3n Tetraploid (四倍体) 4n Pentaploid (五倍体) 5n Autoploid (同源多倍体) Multiples of the same genome Allopolyploid (异源多倍体) (Amphidiploid),Multiples of different genomes,Xunchao Xiang Southwest University of Science and Technology,Characteristics of polyploid,(1). Polyploid often increases plant size
10、(included cell, organelle etc.).,Xunchao Xiang Southwest University of Science and Technology,Characteristics of polyploid,(2) Polyploid often increases plant vigor (heterosis). (3). Fertility of gametes are often reduced, even infertile completely.,Xunchao Xiang Southwest University of Science and
11、Technology,Hypoploid and Hyperploid,Hypoploid (亚倍体): the individual that its chromosome number is loss than diploid. For example, monosomic, double monosomic, nullisomic, etc. Hyperploid (超倍体): the individual that its chromosome number is more than diploid. For example, trisomic, tetrasomic, etc.,Xu
12、nchao Xiang Southwest University of Science and Technology,7.2 Nonjunction: The Origin of Aneuploidy,Xunchao Xiang Southwest University of Science and Technology,7.3 Monosomy(单体性),Monosomy: The loss of one chromosome in a normal diploid produces a (2n 1) complement and is called monosomy or monosomi
13、c. For example, T urner syndrome(45, XO).,Xunchao Xiang Southwest University of Science and Technology,7.3 Monosomy,Cri-du-Chat Syndrome(猫叫综合症) This syndrome is associated with the loss of part of the short arm of chromosome 5, strictly, this case should be referred to as segmental deletion. Its gen
14、etic constitution may be designated as 46, 5p, meaning that such an individual has all 46 chromosomes but that some of the p arm of one member of the chromosome 5 pair is missing. Incidence: 1/50,000 live births.,Xunchao Xiang Southwest University of Science and Technology,Cri-du-Chat Syndrome,Xunch
15、ao Xiang Southwest University of Science and Technology,7.4 Trisomy(三体性),The addition of an extra chromosome products somewhat more viable individuals in both animal and plant species than does the loss of a chromosome. Down Syndrome It is the only human autosomal trisomy in which a significant numb
16、er of individuals survive longer than a year past birth. It results from trisomy of chromosome 21, and is also called simply trisomy 21(is designated 47, 21) Incidence: 1/800 live birth.,Xunchao Xiang Southwest University of Science and Technology,Down Syndrome,Xunchao Xiang Southwest University of
17、Science and Technology,Down Syndrome,Xunchao Xiang Southwest University of Science and Technology,Viability in Human Aneuploid Conditions,Patau Syndrome ( 47,13 ),Edwards syndrome (47, 18 ) They result in severe malformations and early lethality.,Xunchao Xiang Southwest University of Science and Tec
18、hnology,Viability in Human Aneuploid Conditions,At least 1520 percent of all conceptions terminate in spontaneous abortion. About 30 percent of all spontaneously aborted fetuses demonstrate some form of chromosomal anomaly, and approximately 90 percent of all chromosomal anomalies are terminated pri
19、or to birth as a result of spontaneous abortion. A large percentage of those demonstrating chromosomal abnormalities are aneuploids. The aneuploid with highest incidence among abortuses is the 45,X condition.,Xunchao Xiang Southwest University of Science and Technology,7.5 Polyploidy and Its Origins
20、,Xunchao Xiang Southwest University of Science and Technology,7.5 Polyploidy and Its Origins,1. Origin of polyploidy Polyploid originates in two ways: (1) Autopolyploid: the addition of one or more extra sets of chromosomes, identical to the normal haploid complement of the same species. (2) Allopol
21、yploidy(异源多倍体): the addition of one or more extra sets of chromosomes, different to the normal haploid complement of the same species.,Xunchao Xiang Southwest University of Science and Technology,7.5 Polyploidy and Its Origins,Amphidiploid,Xunchao Xiang Southwest University of Science and Technology
22、,Autopolyploid(同源多倍体),Having being replicated, do not appear,Xunchao Xiang Southwest University of Science and Technology,Allopolyploidy(异源多倍体),Xunchao Xiang Southwest University of Science and Technology,2. 多倍体的形成途径及其应用,(1)未减数配子结合减数分裂 (2)体细胞染色体数加倍有丝分裂 (3)人工诱导多倍体的应用,Xunchao Xiang Southwest Universit
23、y of Science and Technology,(1)未减数配子结合,桃树(2n=2x=16=8)的未减数配子(n=2x=16)融合形成同源多倍体 未减数配子未减数配子 四倍体(2n=4x=32=8) 未减数配子正常配子 三倍体(2n=3x=24=8),Xunchao Xiang Southwest University of Science and Technology,(1)未减数配子结合,种间杂种F1未减数配子融合形成异源多倍体 例:,Xunchao Xiang Southwest University of Science and Technology,(2)体细胞染色体数加倍
24、,体细胞染色体加倍的方法 最常用的方法:秋水仙素处理分生组织 阻碍有丝分裂细胞纺锤丝(体)的形成 处理浓度:0.01-0.4%(0.2%) 处理时间:视材料而定 间歇处理效果更好 同源多倍体的诱导 诱导二倍体物种染色体加倍同源多倍体(偶倍数) 异源多倍体的诱导 诱导杂种F1染色体加倍双二倍体 诱导二倍体物种染色体加倍同源多倍体杂交双二倍体,Xunchao Xiang Southwest University of Science and Technology,(3)人工诱导多倍体的应用,1.克服远缘杂交的不孕性 2.克服远缘杂种的不实性 3.创造种间杂交育种的中间亲本 实质是克服远缘杂交不育性
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