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1、 Lesson ThreeCellular Reproduction:Mitosis and Meiosis细胞的增殖：有丝分裂和减数分裂细胞的增殖：有丝分裂和减数分裂1英语佳句300例之oTherapidexpansionofurbanareashas in many casesencroached（侵犯）onvaluablecultivatable（可耕种的）land,andled to a general recognition（引起了广泛关注）（引起了广泛关注） thatdevelopmentmustnotbecarried at the cost ofagriculture.Theg
2、overnmenthas attached greater importance to（重（重视）视） theproblemandanincreasingnumberofredundant（多余的）projectsarebeingterminated.o城区的迅速扩大在很多情况下侵占了宝贵的可耕地，使人们普遍认识到发展不能以牺牲农业为代价。政府更加重视这个问题，越来越多的不必要的工程被终止。2Metaphase plate赤道板，中期板3Cell plate 细胞板4Chromatid 染色单体Centromere sentrmi 着丝粒着丝粒染色体上一段非编码的染色体上一段非编码的DNA,
3、对动粒（或动粒蛋白）有组织和整合作用对动粒（或动粒蛋白）有组织和整合作用 5Chalone klun :抑素成熟的和分化的细胞产生的蛋白质，抑制DNA合成、原始细胞分裂，具有组织特异性，但无种属特异性。oMammalian mmeljn : n.哺乳动物 adj.哺乳动物的oHomogenatehmdineit: n.均匀混合物, 生(组织)匀浆6Nucleosome nju:klisum 核小体7Chromatin krumtin 染色质coreparticle核心颗粒dinucleosomemodel双核小体模型chromatinfibermodel染色质纤维模型8Cytokinesis
4、saitukaini:sis 胞质分裂9oDiploid diplid 二倍体，双倍的nBi, di, dipl, twi, du /前缀/ 二，双，两oHaploid hplid 单倍体nHapl(o)-, mono-, uni- /前缀/ 单，一，独nMonoxide mnksad 一氧化物nunicellular ju:niseljul adj. 单细胞的10Histone 组蛋白五种类型：H1、H2A、H2B、H3、H411Homologoushmls pair 同源染色体对12Karyotype kritaip 核型，染色体组型13Interphase int(:)feiz 分裂间期
5、14Prophase 分裂前期Spindle 纺锤体纺锤体15Anaphase nfeiz 分裂后期oPole n.棒, 柱, 杆, 竿, 极, 磁极, 电极;vt.用竿支撑, 用棒推;vi.撑篙16Telophase telfeiz 分裂末期17Metaphase metfeiz 分裂中期18Mitosis 有丝分裂19oAutosome :tsumn.正染色体, 常染色体oKinetochore kini:tk:n.生动粒；着丝粒oPartition p:tin n.分割, 划分, 瓜分, 分开, 隔离物;vt.区分, 隔开, 分割20oPinch n.捏,撮,收缩,紧急关头,匮乏, 压力
6、nvt. 掐,夹痛, 修剪, 勒索, 使感缺乏, 使萎缩, 偷nvi.收缩, 节省oProgeny prdni: n.后裔,后代oa-,an- (元音前用)无，非nasexualeiseksjul 无性繁殖的; nabacterial 非细菌性的;n amoral em:rl无道德感的n asymmetricsmetrk 不对称的;21Meiosis maiusis 减数分裂22英语佳句300例之oThere has been a dramaticdrmtik （戏剧性的）（戏剧性的） increase inthespreadofAIDSinrecentyears,with a new stu
7、dy projecting thatthedreaded（令人畏惧的）diseasewillaffectover30millionpeopleworldwidebytheyear2005.近年来，艾滋病蔓延的幅度进一步扩大，一项新的研究预测，到2005年，世界上有超过三千万人将感染这一可怕的疾病。23Text:1 The nucleus and chromosome24orepositoryrpzt:ri:储藏室ocoilkilv.螺旋supercoiloclustern.丛；簇，串；群ostretchstretn.伸展；延伸owindaround缠绕ohistonesn.组蛋白nonhist
8、one非组蛋白的obeadlike串珠状的onucleosomes核小体odensedens致密的ocombinekmbainv.使结合ochromatin.染色质ochromosome染色体25oThe cell nucleus is the main repository of genetic information. Within the nucleus are the chromosomes - tightly coiled strands of DNA and clusters of associated proteins. Long stretches of the continu
9、ous DNA molecule wind around these clusters of proteins, or histones, forming beadlike complexes known as nucleosomes. o细胞核是贮藏遗传信息的主要场所。细胞核内有染色体，细胞核是贮藏遗传信息的主要场所。细胞核内有染色体，包括由包括由DNA紧密盘绕成的螺旋线以及相关的成簇蛋白紧密盘绕成的螺旋线以及相关的成簇蛋白质。连续的质。连续的DNA链缠绕成簇的组蛋白链缠绕成簇的组蛋白, 形成珠链状的形成珠链状的核小体。核小体。26oMore coiling and supercoiling
10、 produces a dense chromosome structure. Each long strand of DNA combines with histones and nonhistone proteins to make up the substance chromatin.o这些螺旋和超螺旋形成致密的染色体结构。每个长链这些螺旋和超螺旋形成致密的染色体结构。每个长链DNA与组蛋白和非组蛋白一起构成染色质。与组蛋白和非组蛋白一起构成染色质。27opictorialpkt:ri:ladj.绘画的；有图片的；图画似的ocondensekndensvt.变浓缩；使更紧密okaryot
11、ypekritaipn.染色体组型osexchromosome性染色体ohomologouspairs同源染色体对oautosomes常染色体oorganism:nizm有机体odiploiddiplid二倍体ohaploidhplid单倍体28oA pictorial display of an organisms chromosomes in the coiled, condensed state is known as a karyotype. Karyotype reveal that in most cells all but sex chromosomes are present
12、as two copies, referred to as homologous pairs. Non-sex chromosomes are called autosomes. o对生物这种致密的、双螺旋状态的图示我们称为染色对生物这种致密的、双螺旋状态的图示我们称为染色体组。通过染色体组，我们发现除了性染色体外，大体组。通过染色体组，我们发现除了性染色体外，大多数细胞的染色体成对出现，称同源染色体对。非性多数细胞的染色体成对出现，称同源染色体对。非性染色体称常染色体。染色体称常染色体。29oOrganisms whose cells contain two sets of parental
13、prentl chromosomes are called diploid; those with cells containing a single set of parental chromosomes are called haploid.o生物体内的细胞含有两套父母本染色体的称二倍体；生物体内的细胞含有两套父母本染色体的称二倍体；含有单套染色体的称单倍体。含有单套染色体的称单倍体。o多倍体：带有两套以上同源染色体的细胞或个体。多倍体：带有两套以上同源染色体的细胞或个体。302 The cell cycleThecycleisdividedintodistinctphases:G1(ga
14、p1)S(synthesis),G2(gap2),andM(mitosis).Asyoucansee,mitosisonlyoccupies（占据）afraction（小部分）ofthecycle.Therestofthetime-phasesG1throughG2-isknownasinterphase.312 The cell cycle32oregular 有规律的有规律的odivide 划分划分 分离分离orepeat vt. 重复重复 oin effect 实际上实际上osingle-celled 单细胞的单细胞的oimmortal i m :tl adj. 不死的；永恒的不死的；永
15、恒的omulticellular m lti seljul多细胞的多细胞的omuscle msl n. 肌肉肌肉onerve n:v n. 神经神经oaltogether 完全地完全地odivision divin 分分开开33oThe cell cycle is a regular sequence in which the cell grows, prepares for division, and divides to form two daughter cells, each of which then repeats the cycle. Such cycling in effect
16、 makes single-celled organisms immortal. o在细胞生长过程中，细胞循环遵循固定程序，首先进在细胞生长过程中，细胞循环遵循固定程序，首先进行分裂准备，分裂成行分裂准备，分裂成2个子细胞，子细胞再循环。此个子细胞，子细胞再循环。此循环的存在让单细胞生物得以循环的存在让单细胞生物得以“长生不死长生不死”。34oMany cells in multicellular organisms, including animal muscle and nerve cells, either slow the cycle or break out of it altoge
17、ther.o多细胞生物中的许多细胞，包括动物肌细胞和神经多细胞生物中的许多细胞，包括动物肌细胞和神经细胞，要么细胞循环速度降低，要么全部从这个循细胞，要么细胞循环速度降低，要么全部从这个循环中脱离。环中脱离。35ometabolismmaitblzmn. 新陈代谢新陈代谢oreplicatereplketvt. 复制复制ohistone histun 组蛋白组蛋白osynthesizesnsaz vi. 合成合成ointerphase int(:)feizn. （细胞的）间期（细胞的）间期omitosis英英 mitusis 美美 matoss ocondense kndens vt.变稠或变
18、浓，浓缩变稠或变浓，浓缩oproperty prpti n. 特性，属性特性，属性oinhibitor inhibit n. 抑制剂抑制剂ochalones抑素抑素36oThe normal cell cycle consists of four phases. The first three include G1, the period pirid of normal metabolism; S phase, during which normal synthesis of biological molecules continues, DNA is replicated, and hist
19、ones are synthesized; and G2, a brief period of metabolism and additional growth. Together the G1, S, and G2 phases are called interphase. o正常的细胞循环由正常的细胞循环由4个阶段组成。头三个阶段包括个阶段组成。头三个阶段包括G1, 正常新陈代谢；正常新陈代谢；S期期, 生物分子正常合成同时，复制生物分子正常合成同时，复制DNA，合成组蛋白；，合成组蛋白； G2 期，短期的新陈代谢和继续期，短期的新陈代谢和继续生长。生长。G1, S, 和和G2称分裂间期。
20、称分裂间期。37oThe fourth phase of the cell cycle is M phase, the period of mitosis, during which the replicated chromosomes condense and move and the cell divides. It is believed that properties of the cell cytoplasm control the cell cycle, along with externalekst:nl stimulators and inhibitors such as ch
21、alones.o最后是最后是M期有丝分裂期。此期间，复制的染色体浓期有丝分裂期。此期间，复制的染色体浓缩、移动然后细胞分裂。现在普遍接受的是染色质的缩、移动然后细胞分裂。现在普遍接受的是染色质的特征，以及外部刺激物、抑制因子如抑素等控制了细特征，以及外部刺激物、抑制因子如抑素等控制了细胞循环。胞循环。383 Mitosis: partitioning the hereditary material p:tini n.分割分割 hireditri adj. 遗传遗传的的39oBiologistbaldst n. 生物学家生物学家omitotic cyclemittik 有丝分裂有丝分裂周期周期o
22、prophase 前期前期ochromatidkrumtidn. 染色单体染色单体ocentromere sentrmi n. 着丝粒着丝粒ometaphase 中期中期ospindle spndl 生生纺锤体纺锤体oEventuallyiventjuli adv. 终于终于oplane n. 水平；平面水平；平面o right anglel 直角直角oanaphase 后期后期odraw 拖拖otelophase 末期末期40oBiologists divide the mitotic cycle into four phases. At the beginning of prophase
23、the chromosomes each consist of two highly condensed chromatids attached to each other at a centromere. As prophase ends and metaphase begins, the condensed chromosomes become associated with the spindle. o生物学家将有丝分裂划分为生物学家将有丝分裂划分为4个阶段。分裂前期，高个阶段。分裂前期，高度浓缩的两个染色单体通过着丝粒连接在一起。在分度浓缩的两个染色单体通过着丝粒连接在一起。在分裂前期
24、后期和分裂中期前期，浓缩的染色体与纺锤体裂前期后期和分裂中期前期，浓缩的染色体与纺锤体相连。相连。41oEventually the chromosomes become arranged in a plane (called the metaphase plate) at a right angle to the spindle fibers. o最后染色体与纺锤丝垂直的角度排列在赤道板上。最后染色体与纺锤丝垂直的角度排列在赤道板上。oNext, during anaphase, the two sister chromatids of each chromosome split, and
25、one from each pair is drawn toward each pole of the cell. During telophase nuclear envelopesenvlups begin to form around each set of chromosomes, and division of the cytoplasm takes place.o在分裂后期，两个姊妹单体分离，分别被拽向细胞两极。在分裂末期，在分裂后期，两个姊妹单体分离，分别被拽向细胞两极。在分裂末期，在每套染色体周围形成核膜，然后细胞质分裂。在每套染色体周围形成核膜，然后细胞质分裂。42omicr
26、otubule maikrutju:bju:ln. 微管微管ocrucialkru:l adj. 关键性的，决定性的；关键性的，决定性的；ometaphase plate 赤道板赤道板ocentromeric医医着丝粒的着丝粒的okinetochore kini:tk:n. 动粒动粒 43oAs mitosis proceeds, the spindle microtubules play a crucial role in ensuring that both paired and separated chromatids move in the right directions at th
27、e proper times. Each half of the spindle forms as microtubules extend from each pole of a dividing cell to the region of the metaphase plate. During prophase, other microtubules, the centromeric fibers, extend outward from the spindle poles to structures on the chromosomes called kinetochores. Durin
28、g anaphase the fibers begin to shorten, and the chromatids begin to move apart.o在有丝分裂过程中，纺锤体微管在确保染色体对和染色单体在在有丝分裂过程中，纺锤体微管在确保染色体对和染色单体在适当时间向正确方向分离时起着关键作用。纺锤体微管由两极适当时间向正确方向分离时起着关键作用。纺锤体微管由两极向赤道板延伸。在分裂前期，其它微管，着丝粒纤维由纺锤体向赤道板延伸。在分裂前期，其它微管，着丝粒纤维由纺锤体的两极延伸到染色体的动粒。在分裂后期，纤维开始变短，染的两极延伸到染色体的动粒。在分裂后期，纤维开始变短，染色单体分
29、离。色单体分离。44ocentriole sentriuln. 细胞中心粒，中心体细胞中心粒，中心体 ofungal fladj. 真菌的真菌的 fungus 真菌真菌ocleavage furrow kli:v d f :r 卵裂沟卵裂沟ocontracting ring of microfilament微丝收微丝收缩环缩环45oThe spindle forms differently in plant and animal cells. In animals it is associated with centriole, while in plant and fungal cells
30、spindle formation is associated with regions called microtubule organizing centers.o植物和动物细胞纺锤体的形成不同。动物细胞中，植物和动物细胞纺锤体的形成不同。动物细胞中，纺锤体与中心粒相连；而在植物和真菌细胞中，纺纺锤体与中心粒相连；而在植物和真菌细胞中，纺锤体与微管组织中心相连。锤体与微管组织中心相连。 464 Cytokinesis: partitioning the cytoplasm卵裂沟47ocytokinesissaitukaini:sis胞质分裂oactinfilaments肌动纤维丝oequa
31、torikweitn.赤道opinchpintvt.捏，掐；挤痛，夹痛oCellwall细胞壁odeposite沉积ocellplate细胞板48oThe division of the cell cytoplasm at the end of mitosis is called cytokinesis. In animal cells it takes place as a ring of actin filaments contracts around the cell equator, pinching the cell in two. In plant cells, which are
32、 bounded by a cell wall, cytokinesis involves the building of a new cell plate across the dividing cell at its equator. Cell wall material is then depositeddipzitid in the region of the cell plate.o在动物细胞中，环形肌动蛋白丝延赤道板收缩而使细胞在动物细胞中，环形肌动蛋白丝延赤道板收缩而使细胞一分为二。在细胞壁包围的植物细胞中，胞质分离需要一分为二。在细胞壁包围的植物细胞中，胞质分离需要在细胞中央形
33、成新的细胞板。在细胞中央形成新的细胞板。 细胞壁成份随后在此区域细胞壁成份随后在此区域沉积。沉积。49英语佳句300例之oWorkingwiththedisabledcannot help but（不得不（不得不) leave one impressed with(留下深刻印象留下深刻印象)theirindefatigablendftgbl不屈不挠的desire.o与残疾人一起工作使一个人不得不对他们坚持不懈的渴望印象深刻。505 Meiosis: the basis of sexual reproduction synapsis sinpsis 生染色体结合; 联会sexual reprod
34、uctionseksjul ri:prdkn有性生殖 mitotic spindlemittik有丝分裂纺锤丝51meiosisFig. meiosis in a plant pollen grain.花粉粒pln52oreproductive organs ri:pr d kt v 生殖器官生殖器官osequential skwenl 有序的有序的onuclear divisions 核分裂核分裂omeiosis I and meiosis 减数第一次分裂和第二次分裂减数第一次分裂和第二次分裂53oMeiosis is a special form of cell division that
35、 takes place in the reproductive organs that produce sex cells. Like mitosis, it takes place after DNA replication has occurred and involves two sequential nuclear divisions (meiosis I and meiosis ). These divisions result in four daughter cells, each with half the number of chromosomes of the paren
36、t cell. o减数分裂是细胞分裂的特殊形式，发生在产生性细胞的性器官减数分裂是细胞分裂的特殊形式，发生在产生性细胞的性器官中。跟有丝分裂相似，它也是发生在中。跟有丝分裂相似，它也是发生在DNA复制后，但有连续的复制后，但有连续的两个核分裂。分裂的结果产生两个核分裂。分裂的结果产生4个子细胞，分别含有亲本一半个子细胞，分别含有亲本一半的染色体数。的染色体数。54ophenomenon fi n minn 现象现象ocrossing overkrsi uv 交换，互换交换，互换oexchangeiksteind 交换交换ohomologous chromosomes 同源染色体同源染色体opr
37、ogeny prdni: 子代子代 后裔后裔oidenticalaidentikl adj. 同一的；完全同同一的；完全同样的样的55oThe phenomenon of crossing over during meiosis results in exchanges of genetic information between chromosomes. Hence, the homologous chromosomes distributed to different progeny cells are not identical.o有丝分裂过程中的交换现象的结果是染色体间的遗有丝分裂过程
38、中的交换现象的结果是染色体间的遗传信息交换。因此，同源染色体是分配到哪个子细传信息交换。因此，同源染色体是分配到哪个子细胞并不确定。胞并不确定。56oundergo ndu 经历，遭受经历，遭受osynapsis sinpsis 联会联会opairing 配对配对obridging 桥接桥接osynaptonemal complex 联会复合体联会复合体oalign lan vi. 排列；成一条线排列；成一条线ohalving h:vi n. 对分，二等分，减半对分，二等分，减半oresult from 产生于产生于 由由.引起引起57oAs in mitosis two chromatids
39、 exist for each chromosome at the beginning of prophase 1. During this phase the homologous chromosomes undergo synapsis, or pairing, which is brought about by a bridging structure of proteins and RNA called the synaptonemal complex. The homologous pairs stay together when they align on the metaphas
40、e plate. o跟在有丝分裂中一样，在分裂前期每条染色体存在两个同源染跟在有丝分裂中一样，在分裂前期每条染色体存在两个同源染色单体。在此阶段，同源染色体经历联会（或配对）。期间通色单体。在此阶段，同源染色体经历联会（或配对）。期间通过蛋白质和过蛋白质和RNA组成的连接结构联会复合体。组成的连接结构联会复合体。58oUnlike the anaphase of mitosis, however, during anaphase I the two chromatids of each chromosome stay joined at the centromere and move toge
41、ther to one of the two poles of the cell. It is this event that results in the halving of the chromosome number in the four daughter cells that result from meiosis.o与有丝分裂不同的是，每组染色体的两个染色单体连与有丝分裂不同的是，每组染色体的两个染色单体连接在着丝点上并一起移向细胞两极的一级。由此而导接在着丝点上并一起移向细胞两极的一级。由此而导致致4个子细胞染色体数减半。个子细胞染色体数减半。59oenclose inkluz
42、把把围起来围起来onucleus 细胞核细胞核 复数复数 nucleionuclear 细胞核的细胞核的orandomly rndmli 随机地随机地ometaphase plate 中期板中期板odistribute dis tribju:t vt. 分配分配60oDuring telophase I nuclear envelopes enclose the chromosomes in nuclei, and in most species cytokinesis (the first nuclear division) follows. The second nuclear divis
43、ion begins with metaphase , in which the chromosomes in each daughter cell again align on a metaphase plate. The centromeres finally divide, and each sister chromatid moves to one of the poles of the spindle. The next phase is telophase , followed again by cytokinesis. The result of the entire proce
44、ss is four haploid cells in which parental chromosomes are randomly distributed.o第二次核分裂开始于分裂中期，子细胞中染色体重新排列在赤第二次核分裂开始于分裂中期，子细胞中染色体重新排列在赤道板上。着丝粒最终分离，每个姊妹染色单体分向两极。接着道板上。着丝粒最终分离，每个姊妹染色单体分向两极。接着胞质分裂。产生胞质分裂。产生4个单倍体，父母染色体随机分配。个单倍体，父母染色体随机分配。 61oAsexualeiseksjuladj.无性的；无性生殖的oversusv:ss与.比较oGametesmi:ts配子626
45、 Asexual versus sexual reproduction无性繁殖与有性生殖的比较无性繁殖与有性生殖的比较oAsexual reproductionnNO exchange of genetic materialnMitosisoSexual reproductionnExchange of genetic materialn MeiosisnGametes63orespectivelyrispektivliadv.各自地；分别地opasson传递ohereditaryinformationhireditri遗传信息oasexualreproduction无性繁殖osexualre
46、production有性繁殖ogiveriseto生产ooffspringfspri子代ogeneticclones基因克隆同样的基因opreservepriz:v保持ogenetic complement kmplimnt 基因互补基因互补ospecializationspelazen特殊化64oMitosis and meiosis, respectively, make simple cell division and sexual reproduction possible. Each means of passing on hereditary information has adv
47、antages. In asexual reproduction the parent organism gives rise to offspring that are genetic clones of the parent. The advantages of this type of reproduction are that it preserves the parents successful genetic complement , requires little or no specialization of reproductive organs, and is more r
48、apid than sexual reproduction. o有丝分裂和减数分裂在传递遗传信息过程中各有优势。体细胞有丝分裂和减数分裂在传递遗传信息过程中各有优势。体细胞的繁殖就是父母本的克隆，其优势是保留了父母本的成功遗传的繁殖就是父母本的克隆，其优势是保留了父母本的成功遗传信息，不需要特殊器官，比性复制快的多。信息，不需要特殊器官，比性复制快的多。65omode mud 方式方式 模式模式ocatastrophicktstrfkadj.灾难的ovariability verbltn.变化性ogenetic variability 基因的可变性opopulation群体ogenetical
49、ly dnetkli identical aidentikl organisms 遗传性相同的有机体oprime 最好的首要的oeliminationlmnen 排除出去odeleterious mutationsdeltri:s mju:ten有害突变oarise raiz 产生ospread spred延伸传播66oA major disadvantage of the asexual mode is that a single catastrophic event or disease may destroy an entire population of genetically ide
50、ntical organisms. A prime benefit of sexual reproduction is that it provides genetic variability and a ready mechanism for the elimination of deleterious mutations. It also allows new gene forms to arise and spread through populations.o但一个简单灾难性事件或疾病都可能摧毁一个细胞群体。但一个简单灾难性事件或疾病都可能摧毁一个细胞群体。有性繁有性繁殖殖的优势是它提供了遗传可变性和现存排除有害突变的机制。也的优势是它提供了遗传可变性和现存排除有害突变的机制。也可以产生新的基因并在种群中蔓延。可以产生新的基因并在种群中蔓延。67作业o用英文简单描述有丝分裂和减数分裂的过程。68
