第二章 遗传的物质基础.ppt

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　　标题： 第二章 遗传的物质基础

　　副标题： 2.1 细胞的结构 2.2 染色体 2.3 染色体的传递(细胞分裂)

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　　标题： 2.1 细胞的结构

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　　标题： 生命的细胞理论(1)

　　正文： 1) 每种生物都是由1个或多个细胞组成的 (Every organism is consisted of one 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)

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　　正文： 4〕可独自生存或具此潜力 Can survive on its own or has potential to do so 5〕可进行高度有序的代谢 Is highly organized for metabolism 6〕可感受并对环境的变化作出反应 Senses and responds to environment 7〕具有增殖的潜力 Has potential to reproduce

　　生命的细胞理论(2)

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　　标题： 细胞的结构(Structure of Cells)

　　正文： 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)

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　　标题： 真核细胞 (Eukaryotic Cells)

　　正文： 具细胞核和其他细胞器(Have a nucleus and other organelles) 真核生物(Eukaryotic organisms) 植物(Plants) 动物(Animals) 原生生物(Protistans) 真菌(Fungi)

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　　标题： 动物细胞(Animal Cells)

　　正文：

　　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

　　中心体 Centrosome

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　　标题： 植物细胞(Plant Cells)

　　正文：

　　正文： 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

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　　细胞核(Nucleus)

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　　G0和G1期染色体:染色质(Chromosomes at G1 phase: Chromatin)

　　2 nm

　　30 nm

　　Coding (blue) and non-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)

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　　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

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　　G2期细胞中染色体通常存在的状态(The “usual” state of chromosomes in G2 cells (after DNA replication)

　　两个G1期染色质的并排排列，之间有cohesins蛋白连接

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　　前期染色体(Chromosomes at prophase)

　　“Old” coding strand

　　“New” coding strand

　　(Gp:) Mitotic Chromosome

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　　When cells entry mitosis: Chromatin condense together into a mitotic chromosome

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　　The mechanism of chromosome condensation is not completely understood but note…

　　(Gp:) P

　　(Gp:) P

　　(Gp:) Phosphorylation of histones & proteins in condensin complex

　　Condensin complex

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　　DNA package and chromosome condensation with cell cycle progression from G2 to metaphase

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　　标题： Human T-lymphocyte metaphase

　　Karyotype 46, XY

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　　中期染色体(Chromosomes at Metaphase)

　　(Gp:) 5 um

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　　正文： 着丝粒 Centromeres the largest constriction of the chromosome.

　　100,000s of 171 base pair repeat, called alpha satellite sequences Centromere associated proteins are bound: Kinetochore Site of attachment of spindle fibers

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　　标题： Centromere and Kinetochore

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　　正文： 端粒 Telomeres

　　At the tips of chromosomes: Protect Many repeats of the sequence TTAGGG Subtelomeres have more varied short repeats

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　　人类全着丝粒探针 (pan-centromeric，Green) 和全端粒探针 (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 Shi unpublished

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　　标题： 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

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　　标题： 人染色体G-带核型模式图Schematic of Karyotype

　　正文： 带型 Banding pattern 大小 Sizes 着丝粒位置 Centromere position：中、近中、端着丝粒 其他结构变化 Other structural differences：次缢痕、随体 染色体数目 Number differences

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　　标题： 不同物种染色体数目不同

　　正文： 物种Species 二倍体 # 单倍体 # 牛Cattle 60 30 猪Swine 38 19 羊Sheep 54 27 马Horse 64 32 人Human 46 23 鸡Chicken 78 39 山羊Goat 60 30 驴Donkey 62 31

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　　标题： 染色体 The Chromosomes

　　正文： 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. 在一个物种的绝大多数(全部)体细胞中，染色体数目相同Chromosomes numbers are the same in vast majority (every) somatic cell for each species.

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　　标题： 染色体 The Chromosomes

　　正文： 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 chromosomes are different, XY it results in a male.

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　　标题： 染色体传递：细胞分裂Chromosome transmitting: Cell Division

　　正文： Meiosis 减数分裂 Is the form of cell division which results reducing the chromosome number from the diploid # to the haploid #. Occurs only in the sex cells, sperm and ovum. Mitosis 有丝分裂 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.

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　　标题： 细胞周期 The Cell Cycle

　　正文： 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 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、末期和细胞质分裂〕

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　　正常有丝分裂

　　Abscission

　　Shi & King, Nature 437:1038-1042, 2005

　　绿色荧光蛋白(GFP)-组蛋白H2B融合基因，转入细胞中，使其表达

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　　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

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　　标题： Mitosis in Detail

　　正文： During mitosis, the spindle distributes the chromosomes to each daughter 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.

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　　标题： G2

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　　标题： Early Prophase*Chromosomes condense*Nuclear envelope disappears*Centrioles move to opposite sides of the cell

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　　标题： Late ProphaseSpindle forms and attaches to centromeres on the chromosomes

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　　标题： Metaphase*Chromosomes lined up on equator of spindle*Centrioles at opposite ends of cell

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　　标题： Anaphase*Centromeresdivide: each 2-chromatid chromosome becomes two 1-chromatid chromosomes*Chromosomes pulled to opposite poles by the spindle

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　　标题： Telophase* Chromosomes  decondense* Nuclear envelope  reappears* Cytoplasm divided  into 2 cells

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　　标题： Cytokinesis in Animal Cells

　　正文： In animal cells, a cleavage furrow begins at the end of anaphase. A band of actin and myosin filaments, called the contractile 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.

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　　标题： Cytokinesis in animal cells

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　　正常有丝分裂

　　Abscission

　　Shi & King, Nature 437:1038-1042, 2005

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　　标题： Mitosis: Maintaining Chromosome Number

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　　标题： Meiosis: Halving chromosome number

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　　标题： Meiosis: Two Divisions

　　正文： Two consecutive nuclear divisions Meiosis I Meiosis II DNA is NOT duplicated between divisions Four haploid nuclei are formed

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　　标题： Stages of Meiosis

　　正文： Meiosis I Prophase I Metaphase I Anaphase I Telophase I

　　正文： Meiosis II Prophase II Metaphase II Anaphase II Telophase II

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　　减数分裂前期模式图

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　　Synaptonemal Complex (SC) behavior in meiosis I prophase

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　　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、RNA组成，含有微量的DNA

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　　标题： Meiosis I - Stages

　　(Gp:) Prophase I

　　(Gp:) Metaphase I

　　(Gp:) Anaphase I

　　(Gp:) Telophase I

　　Crossing over

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　　标题： Meiosis I

　　Each homologue in the cell pairs with its partner

　　the partners separate

　　Random alignment of chromosomes at metaphase I

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　　标题： Meiosis II

　　正文： The two sister chromatids of each duplicated chromosome are separated from each other

　　one chromosome (duplicated)

　　two chromosomes (unduplicated)

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　　标题： 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)

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　　标题： 卵子发生Oogenesis

　　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)

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　　标题： 人类生命周期 Life cycle of humans

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　　标题： 受精 Fertilization

　　正文： 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

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　　标题： 导致子代变异的因素 Factors Contributing to Variation Among Offspring

　　正文： 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〕

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　　MITOSIS Occurs in most types of eukaryotic cells.

　　MEIOSIS Occurs in formation of gametes in eukaryotic cells

　　有丝分裂和减数分裂比较

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　　MITOSIS No pairing of Homologous chromosomes

　　MEIOSIS Homologous chromosomes pair in synapsis; crossing over may occur.

　　有丝分裂和减数分裂比较

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　　MITOSIS Chromosome number is maintained.

　　MEIOSIS Chromosome number is reduced from diploidy to haploidy.

　　有丝分裂和减数分裂比较

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　　MITOSIS One division

　　MEIOSIS Two divisions

　　有丝分裂和减数分裂比较

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　　MITOSIS Two daughter cells are produced.

　　MEIOSIS Four daughter cells are produced.

　　有丝分裂和减数分裂比较

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　　MITOSIS Daughter cells are identical to each other and to parent cell

　　MEIOSIS Daughter cells contain varying combinations of chromosomes

　　有丝分裂和减数分裂比较

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　　正文： Mitosis Functions Asexual reproduction Growth, repair Occurs in somatic cells Produces clones

　　标题： Mitosis & Meiosis Compared

　　正文： Meiosis Function Sexual reproduction Occurs in germ cells Produces variable offspring

　　有丝分裂和减数分裂比较

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　　标题： 前期 (Prophase vs. Prophase I)

　　正文： 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 become zippered together and crossing over occurs.)

　　有丝分裂和减数分裂比较

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　　标题： 分裂后期

　　正文： 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

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　　标题： 分裂结果(Results of Mitosis and Meiosis)

　　正文： 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