1、2.1 細(xì)胞的結(jié)構(gòu)細(xì)胞的結(jié)構(gòu)(Structure of Cells)All start out life with:細(xì)胞膜(Plasma membrane, encircling a region where DNA is stored)細(xì)胞質(zhì)(Cytoplasm) Two types:原核(Prokaryotic)真核(Eukaryotic) 真核細(xì)胞 (Eukaryotic Cells)具細(xì)胞核和其他細(xì)胞器(Have a nucleus and other organelles)真核生物(Eukaryotic organisms)植物(Plants)動(dòng)物(Animals)原生生物(Prot

2、istans)：所有不是動(dòng)物、植物或真菌的真核生物，包括纖毛蟲、鞭毛蟲等（草履蟲、錐蟲、瘧原蟲）真菌(Fungi)錐蟲、披發(fā)蟲等；纖毛蟲綱包括喇叭蟲、草履蟲、四膜蟲、鐘形蟲、櫛毛蟲等；肉足綱包括放射蟲、衣殼蟲、沙殼蟲、太陽(yáng)蟲、變形蟲、有孔蟲等；孢子蟲綱就一種典型的，是瘧原蟲。 動(dòng)物細(xì)胞(Animal Cells)質(zhì)膜Plasma membrane細(xì)胞核Nucleus核糖體Ribosomes內(nèi)質(zhì)網(wǎng)Endoplasmic reticulum高爾基體Golgi body小泡Vesicles線粒體Mitochondria溶酶體Lysosome細(xì)胞骨架Cytoskeleton中心體 Centrosome

3、植物細(xì)胞(Plant Cells)細(xì)胞壁Cell wall中央液泡Central vacuole葉綠體Chloroplast質(zhì)膜Plasma membrane細(xì)胞核Nucleus核糖體Ribosomes內(nèi)質(zhì)網(wǎng)Endoplasmic reticulum高爾基體Golgi body小泡Vesicles線粒體Mitochondria溶酶體Lysosome細(xì)胞骨架Cytoskeleton細(xì)胞核(Nucleus)G0和G1期染色體:染色質(zhì)(Chromosomes at G1 phase: Chromatin)2 nm30 nmCoding (blue) andnon-coding strands (gr

4、ey) of DNAG0和G1期細(xì)胞中染色體通常存在的狀態(tài)(The “usual” state of chromosomes in G0 and G1 cells)7S-G2期染色體:染色質(zhì)(Chromosomes at S-G2 phase: Chromatin)“Old” coding strand“New” coding strandSpecial DNA binding proteins e.g. cohesins8G2期細(xì)胞中染色體通常存在的狀態(tài)(The “usual” stateof chromosomes inG2 cells (after DNA replication)兩個(gè)G

5、1期染色質(zhì)的并排排列，之間有cohesins蛋白連接前期染色體(Chromosomes at prophase)“Old” coding strand“New” coding strandMitotic Chromosome9When cells entry mitosis: Chromatin condense together into a mitotic chromosome10The mechanism of chromosome condensation is not completely understood but notePPPhosphorylation of histone

6、s & proteins in condensin complexCondensincomplexDNA package and chromosome condensation with cell cycle progression from G2 to metaphase Human T-lymphocyte metaphaseKaryotype 46, XY中期染色體(Chromosomes at Metaphase)5 um著絲粒 Centromeres the largest constriction of the chromosome.100,000s of 171 base pai

7、r repeat, called alpha satellite sequencesCentromere associated proteins are bound: KinetochoreSite of attachment of spindle fibersCentromere and Kinetochore端粒 TelomeresAt the tips of chromosomes: Protect Many repeats of the sequence TTAGGGSubtelomeres have more varied short repeats人類全著絲粒探針 （pan-cen

8、tromeric，Green) 和全端粒探針 （pan-telomeric， Red)熒光原位雜交檢測(cè)染色體的完整性Human N-Tert1 cells have intact chromosomes detected by FISH using telomeric and centromeric probesQinghua ShiunpublishedTell me what I am ?染色體是一個(gè)物種區(qū)分于其他物種的最基本遺傳特征不同物種染色體數(shù)目不同物種Species 二倍體 # 單倍體 #牛Cattle 6030豬Swine 3819羊Sheep 5427馬Horse 6432人H

9、uman 4623雞Chicken 7839山羊Goat 6030驢Donkey 6231染色體最少的生物：一種螞蟻（M. pilosula），單倍體細(xì)胞僅1條染色體染色體最多的生物：？染色體 The Chromosomes染色體在體細(xì)胞中成對(duì)出現(xiàn) Chromosomes occurs in pairs in every somatic cell except in the sperm and ovum.一個(gè)物種的絕大多數(shù)（全部）體細(xì)胞，其染色體數(shù)目相同Chromosomes numbers are the same in vast majority (every) somatic cell

10、for each species. 染色體 The Chromosomes在二倍體細(xì)胞中含2條性染色體 There are 2 sex chromosomes included in the diploid number of the chromosomes.除性染色體以外的染色體統(tǒng)稱為常染色體 All of the other chromosomes are referred to as autosomes. 雌性哺乳類的2條性染色體相同 In mammals if the sex chromosomes are alike, XX it results in a female.雄性哺乳類的

11、2條性染色體不同 If the sex chromosomes are different, XY it results in a male.(例外：毛冠鹿)染色體傳遞：細(xì)胞分裂Chromosome transmitting: Cell DivisionMeiosis 減數(shù)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.

12、Mitosis 有絲分裂Is the form of 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. 正常有絲分裂AbscissionShi & King, Nature 437:1038-1042, 2005綠色熒光蛋白（Green fluorescence prote

13、in, GFP）-組蛋白H2B融合基因，轉(zhuǎn)入細(xì)胞中，使其表達(dá)G2ProphaseMetaphaseAnaphaseTelophaseG1SG2 CheckpointSpindle checkpointA mechanism responds to chromosome missegregation? 細(xì)胞周期示意圖 Cell Cycle ProgressionG1 CheckpointShi, unpublished貝班細(xì)胞周期 The Cell Cycle是一個(gè)細(xì)胞從其形成到其分裂為2個(gè)細(xì)胞的一系列按序發(fā)生的事件 The cell cycle is an orderly sequence o

14、f events that occurs 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、末期和細(xì)胞質(zhì)分裂G2Early Prophase*Chromosomes condense*Nuclear envelope d

15、isappears*Centrioles move to opposite sides of the cellLate ProphaseSpindle forms and attaches to kinetochores on the chromosomesMetaphase*Chromosomes lined up on equator of spindle*Centrioles at opposite ends of cellAnaphase*Centromeres divide: each 2- chromatid chromosome becomes two 1-chromatid c

16、hromosomes*Chromosomes pulled to opposite poles by the spindleTelophase* Chromosomes decondense* Nuclear envelope reappears* Cytoplasm divided into 2 cellsCytokinesis in Animal CellsIn animal cells, a cleavage furrow begins at the end of anaphase.A band of actin and myosin filaments, called the cont

17、ractile ring, slowly 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 cellsMitosis in DetailDuring mitosis, the spindle distributes the chromosomes to each da

18、ughter cell.The spindle 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: Maintai

19、ning Chromosome NumberMeiosis: Halving chromosome numberMeiosis: Two DivisionsTwo consecutive nuclear divisions Meiosis IMeiosis IIDNA is NOT duplicated between divisionsFour haploid nuclei are formed Stages of MeiosisMeiosis I Prophase IMetaphase IAnaphase ITelophase IMeiosis IIProphase IIMetaphase

20、 IIAnaphase IITelophase IIChromosome behavior in meiosis I prophase聯(lián)合復(fù)合體（SC）SC:位于兩條同源染色體之間，沿縱軸方向延伸；兩側(cè)為側(cè)生組分，寬約20-40nm；側(cè)生組分間為中間區(qū)，寬約100nm；中間區(qū)的中央為中央組分，寬約30nm；側(cè)生組分和中央組分之間有橫向排列的纖維，大致成直角相連，稱L-C纖細(xì)；SC主要由堿性蛋白組成AMeiosis arrests at diplotene with various defects in synapsis. A-D Diplotene spermatocytes with var

21、ious synapsis defects. 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) 發(fā)現(xiàn)了多種未見報(bào)道的減數(shù)分裂異常SYCP3: 示聯(lián)會(huì)復(fù)合體側(cè)軸；MLH1：示重組位點(diǎn)；CREST：示著絲粒人精母細(xì)胞減數(shù)分裂I前期Meiosis I - StagesProphase

22、IMetaphase IAnaphase ITelophase ICrossing overRandom alignment of chromosomes at metaphase IHomologues separateSister chromatids separate精子發(fā)生 SpermatogenesisGrowthMitosis I,Cytoplasmic divisionMeiosis II,Cytoplasmic divisionspermatids (haploid)secondary spermatocytes (haploid)primary spermatocyte (d

23、iploid)spermato-gonium (diploid male reproductive cell)卵子發(fā)生OogenesisGrowthMeiosis I,Cytoplasmic divisionMeiosis II,Cytoplasmic division卵子(n) ovum (haploid)初級(jí)卵母細(xì)胞 (2n) primary oocyte (diploid)卵原細(xì)胞 (2n) oogonium (diploid reproductive cell)次級(jí)卵母細(xì)胞 (n) secondary oocyte (haploid)第一極體(n) first polar body (

24、haploid)三個(gè)極體(n) 3 polar bodies (haploid)人類生命周期 Life cycle of humans受精 Fertilization雌雄配子結(jié)合、細(xì)胞核融合 Male and female gametes unite and nuclei fuse兩個(gè)單倍體的配子融合形成二倍體的合子 Fusion of two haploid nuclei produces diploid nucleus in the zygote配子融合是隨機(jī)的 That two gametes unite is random增加了子代的變異 Adds to variation among

25、 offspring導(dǎo)致子代變異的因素 Factors Contributing to Variation Among Offspring前期I同源染色體間的交換 （Crossing over during prophase I中期I染色體在赤道板上的自由排列 （Random alignment of chromosomes at metaphase I配子的自由組合 （Random combination of gametes at fertilizationMITOSIS Occurs in most types of eukaryotic cells.MEIOSISOccurs in f

26、ormation of gametes in eukaryotic cells 有絲分裂和減數(shù)分裂比較MITOSIS No pairing of Homologous chromosomesMEIOSISHomologous chromosomes pair & synapsis; crossing over may occur有絲分裂和減數(shù)分裂比較MITOSIS Chromosome number is maintained.MEIOSISChromosome number is reduced from diploidy to haploidy.有絲分裂和減數(shù)分裂比較MITOSIS One

27、 divisionMEIOSISTwo divisions有絲分裂和減數(shù)分裂比較MITOSIS Two daughter cells are produced.MEIOSISFour daughter cells are produced.有絲分裂和減數(shù)分裂比較MITOSIS Daughter cells are identical to each other and to parent cellMEIOSISDaughter cells contain varying combinations of chromosomes有絲分裂和減數(shù)分裂比較MitosisFunctionsAsexual

28、reproductionGrowth, repair Occurs in somatic cellsProduces clones Mitosis & Meiosis ComparedMeiosisFunction Sexual reproductionOccurs in germ cellsProduces variable offspring有絲分裂和減數(shù)分裂比較前期 (Prophase vs. Prophase I) 有絲分裂前期 (Prophase, Mitosis)同源染色體互不影響 (Homologous pairs do not interact with each other.)減數(shù)分裂前期I (Prophase I, Meiosis) 同源染色體配對(duì)、聯(lián)會(huì)、遺傳物質(zhì)交換（Homologous pairs become zippered to