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1、第二章 遗传的物质基础,2.1 细胞的结构2.2 染色体2.3 染色体的传递(细胞分裂),2.1 细胞的结构,细胞的结构(Structure of Cells),All start out life with:细胞膜(Plasma membrane,encircling a region where DNA is stored)细胞质(Cytoplasm),Two types:原核(Prokaryotic)真核(Eukaryotic),真核细胞(Eukaryotic Cells),具细胞核和其他细胞器(Have a nucleus and other organelles)真核生物(Eukar
2、yotic organisms)植物(Plants)动物(Animals)原生生物(Protistans)：所有不是动物、植物或真菌的真核生物，包括纤毛虫、鞭毛虫等（草履虫、锥虫、疟原虫）真菌(Fungi),锥虫、披发虫等；纤毛虫纲包括喇叭虫、草履虫、四膜虫、钟形虫、栉毛虫等；肉足纲包括放射虫、衣壳虫、沙壳虫、太阳虫、变形虫、有孔虫等；孢子虫纲就一种典型的，是疟原虫。,动物细胞(Animal Cells),质膜Plasma membrane细胞核Nucleus核糖体Ribosomes内质网Endoplasmic reticulum高尔基体Golgi body小泡Vesicles线粒体Mitoc
3、hondria溶酶体Lysosome细胞骨架Cytoskeleton,中心体 Centrosome,植物细胞(Plant Cells),细胞壁Cell wall中央液泡Central vacuole叶绿体Chloroplast,质膜Plasma membrane细胞核Nucleus核糖体Ribosomes内质网Endoplasmic reticulum高尔基体Golgi body小泡Vesicles线粒体Mitochondria溶酶体Lysosome细胞骨架Cytoskeleton,细胞核(Nucleus),G0和G1期染色体:染色质(Chromosomes at G1 phase:Chrom
4、atin),2 nm,30 nm,Coding(blue)andnon-coding strands(grey)of DNA,G0和G1期细胞中染色体通常存在的状态(The“usual”state of chromosomes in G0 and G1 cells),8,S-G2期染色体:染色质(Chromosomes at S-G2 phase:Chromatin),“Old”coding strand,“New”coding strand,Special DNA binding proteins e.g.cohesins,9,G2期细胞中染色体通常存在的状态(The“usual”state
5、of chromosomes inG2 cells(after DNA replication),两个G1期染色质的并排排列，之间有cohesins蛋白连接,前期染色体(Chromosomes at prophase),“Old”coding strand,“New”coding strand,10,When cells entry mitosis:Chromatin condense together into a mitotic chromosome,11,The mechanism of chromosome condensation is not completely understo
6、od but note,Condensincomplex,DNA package and chromosome condensation with cell cycle progression from G2 to metaphase,Human T-lymphocyte metaphase,Karyotype 46,XY,中期染色体(Chromosomes at Metaphase),着丝粒 Centromeres the largest constriction of the chromosome.,100,000s of 171 base pair repeat,called alpha
7、 satellite sequencesCentromere associated proteins are bound:KinetochoreSite of attachment of spindle fibers,Centromere and Kinetochore,端粒 Telomeres,At the tips of chromosomes:Protect Many repeats of the sequence TTAGGGSubtelomeres have more varied short repeats,人类全着丝粒探针（pan-centromeric，Green)和全端粒探针
8、（pan-telomeric，Red),荧光原位杂交检测染色体的完整性Human N-Tert1 cells have intact chromosomes detected by FISH using telomeric and centromeric probes,Qinghua Shiunpublished,Tell me what I am?,染色体是一个物种区分于其他物种的最基本遗传特征,不同物种染色体数目不同,物种Species 二倍体#单倍体#牛Cattle 6030猪Swine 3819羊Sheep 5427马Horse 6432人Human 4623鸡Chicken 7839
9、山羊Goat 6030驴Donkey 6231,染色体最少的生物：一种蚂蚁（M.pilosula），单倍体细胞仅1条染色体,染色体最多的生物：？,染色体 The Chromosomes,染色体在体细胞中成对出现 Chromosomes occurs in pairs in every somatic cell except in the sperm and ovum.一个物种的绝大多数（全部）体细胞，其染色体数目相同Chromosomes numbers are the same in vast majority(every)somatic cell for each species.,染色体
10、 The Chromosomes,在二倍体细胞中含2条性染色体 There are 2 sex chromosomes included in the diploid number of the chromosomes.除性染色体以外的染色体统称为常染色体 All of the other chromosomes are referred to as autosomes.雌性哺乳类的2条性染色体相同 In mammals if the sex chromosomes are alike,XX it results in a female.雄性哺乳类的2条性染色体不同 If the sex ch
11、romosomes are different,XY it results in a male.(例外：毛冠鹿),染色体传递：细胞分裂Chromosome transmitting:Cell Division,Meiosis 减数分裂Is the form of cell division which results reduce the chromosome number from the diploid#to the haploid#.Occurs only in the sex cells,generate sperm and egg.Mitosis 有丝分裂Is the form of
12、 cell division which results in the formation of identical daughter cells,keeps the chromosome number constant.Tissue growth and repair.Occurs throughout the body except in the sex cells.,正常有丝分裂,Abscission,Shi&King,Nature 437:1038-1042,2005,绿色荧光蛋白（Green fluorescence protein,GFP）-组蛋白H2B融合基因，转入细胞中，使其表
13、达,G2,Prophase,Metaphase,Anaphase,Telophase,G1,S,G2 Checkpoint,Spindle checkpoint,A mechanism responds to chromosome missegregation?,细胞周期示意图 Cell Cycle Progression,G1 Checkpoint,Shi,unpublished,贝班,细胞周期 The Cell Cycle,是一个细胞从其形成到其分裂为2个细胞的一系列按序发生的事件 The cell cycle is an orderly sequence of events that o
14、ccurs from the time when a cell is first formed until it divides into two new cells.Most of the cell cycle is spent in interphase（G1，S 和G2.Following interphase,the mitotic stage of cell division occurs.Division(前、中、后、末期和细胞质分裂,G2,Early Prophase*Chromosomes condense*Nuclear envelope disappears*Centrio
15、les move to opposite sides of the cell,Late ProphaseSpindle forms and attaches to kinetochores on the chromosomes,Metaphase*Chromosomes lined up on equator of spindle*Centrioles at opposite ends of cell,Anaphase*Centromeres divide:each 2-chromatid chromosome becomes two 1-chromatid chromosomes*Chrom
16、osomes pulled to opposite poles by the spindle,Telophase*Chromosomes decondense*Nuclear envelope reappears*Cytoplasm divided into 2 cells,Cytokinesis in Animal Cells,In animal cells,a cleavage furrow begins at the end of anaphase.A band of actin and myosin filaments,called the contractile ring,slowl
17、y forms a constriction between the two daughter cells.A narrow bridge between the two cells is apparent during telophase,then the contractile ring completes the division.,Cytokinesis in animal cells,Mitosis in Detail,During mitosis,the spindle distributes the chromosomes to each daughter cell.The sp
18、indle contains fibers made of microtubules that disassemble and assemble.Centrosomes,that duplicate and separate during interphase,organize the spindle.Centrosomes contain centrioles and asters.Mitosis has four phases:prophase,metaphase,anaphase,and telophase.,Mitosis:Maintaining Chromosome Number,M
19、eiosis:Halving chromosome number,Meiosis:Two Divisions,Two consecutive nuclear divisions Meiosis IMeiosis IIDNA is NOT duplicated between divisionsFour haploid nuclei are formed,Stages of Meiosis,Meiosis I Prophase IMetaphase IAnaphase ITelophase I,Meiosis IIProphase IIMetaphase IIAnaphase IITelopha
20、se II,Chromosome behavior in meiosis I prophase,联合复合体（SC）,SC:位于两条同源染色体之间，沿纵轴方向延伸；两侧为侧生组分，宽约20-40nm；侧生组分间为中间区，宽约100nm；中间区的中央为中央组分，宽约30nm；侧生组分和中央组分之间有横向排列的纤维，大致成直角相连，称L-C纤细；SC主要由碱性蛋白组成,A,Meiosis arrests at diplotene with various defects in synapsis.A-D Diplotene spermatocytes with various synapsis def
21、ects.E.Statistics of meiosis progression.F.Testicular section stained with H-E.(Red,green and blue marks SCP3,MLH1 foci and centromeres,respectively.n:the number of cells analyzed),发现了多种未见报道的减数分裂异常,SYCP3:示联会复合体侧轴；MLH1：示重组位点；CREST：示着丝粒,人精母细胞减数分裂I前期,Meiosis I-Stages,Crossing over,Random alignment of c
22、hromosomes at metaphase I,Homologues separate,Sister chromatids separate,精子发生 Spermatogenesis,Growth,Mitosis I,Cytoplasmic division,Meiosis II,Cytoplasmic division,spermatids(haploid),secondary spermatocytes(haploid),primary spermatocyte(diploid),spermato-gonium(diploid male reproductive cell),卵子发生O
23、ogenesis,Growth,Meiosis I,Cytoplasmic division,Meiosis II,Cytoplasmic division,卵子(n)ovum(haploid),初级卵母细胞(2n)primary oocyte(diploid),卵原细胞(2n)oogonium(diploid reproductive cell),次级卵母细胞(n)secondary oocyte(haploid),第一极体(n)first polar body(haploid),三个极体(n)3 polar bodies(haploid),人类生命周期 Life cycle of huma
24、ns,受精 Fertilization,雌雄配子结合、细胞核融合 Male and female gametes unite and nuclei fuse两个单倍体的配子融合形成二倍体的合子 Fusion of two haploid nuclei produces diploid nucleus in the zygote配子融合是随机的 That two gametes unite is random增加了子代的变异 Adds to variation among offspring,导致子代变异的因素 Factors Contributing to Variation Among Of
25、fspring,前期I同源染色体间的交换（Crossing over during prophase I中期I染色体在赤道板上的自由排列（Random alignment of chromosomes at metaphase I配子的自由组合（Random combination of gametes at fertilization,MITOSIS Occurs in most types of eukaryotic cells.,MEIOSISOccurs in formation of gametes in eukaryotic cells,有丝分裂和减数分裂比较,MITOSIS No
26、 pairing of Homologous chromosomes,MEIOSISHomologous chromosomes pair crossing over may occur,有丝分裂和减数分裂比较,MITOSIS Chromosome number is maintained.,MEIOSISChromosome number is reduced from diploidy to haploidy.,有丝分裂和减数分裂比较,MITOSIS One division,MEIOSISTwo divisions,有丝分裂和减数分裂比较,MITOSIS Two daughter cel
27、ls are produced.,MEIOSISFour daughter cells are produced.,有丝分裂和减数分裂比较,MITOSIS Daughter cells are identical to each other and to parent cell,MEIOSISDaughter cells contain varying combinations of chromosomes,有丝分裂和减数分裂比较,MitosisFunctionsAsexual reproductionGrowth,repair Occurs in somatic cellsProduces
28、clones,Mitosis&Meiosis Compared,MeiosisFunction Sexual reproductionOccurs in germ cellsProduces variable offspring,有丝分裂和减数分裂比较,前期(Prophase vs.Prophase I),有丝分裂前期(Prophase,Mitosis)同源染色体互不影响(Homologous pairs do not interact with each other.)减数分裂前期I(Prophase I,Meiosis)同源染色体配对、联会、遗传物质交换（Homologous pairs
29、become zippered together and crossing over occurs.),有丝分裂和减数分裂比较,分裂后期,减数分裂后期I(Anaphase I,Meiosis)同源染色体分开(Homologous chromosomes are separated from each other.)有丝分裂后期/减数分裂后期II(Anaphase/Anaphase II,Mitosis/Meiosis)姐妹染色单体分开(Sister chromatids of a chromosome are separated from each other),有丝分裂和减数分裂比较,分裂结
30、果(Results of Mitosis and Meiosis),有丝分裂(Mitosis)2个二倍体细胞(Two diploid cells produced)2个子细胞均与亲代细胞相同(Each identical to parent)减数分裂(Meiosis)4个单倍体细胞(Four haploid cells produced)4个子细胞互不相同,且有别于亲代细胞(Differ from parent and one another),有丝分裂和减数分裂比较,生命的细胞理论（1）,1)每种生物都是由1个或多个细胞组成的(Every organism is consisted of o
31、ne or more cells)2)细胞是生命的最小单位(Cell is smallest unit of life)3)生命的延续是以单个细胞的生长和分裂为基础的(Continuity of life arises from growth and division of single cells),4可独自生存或具此潜力 Can survive on its own or has potential to do so5可进行高度有序的代谢 Is highly organized for metabolism6可感受并对环境的变化作出反应 Senses and responds to environment7具有增殖的潜力 Has potential to reproduce,生命的细胞理论（2）,
