生物专业英语(9)分析解析备课讲稿

1、生物专业英语(9)分析解析 In cells with a nucleus (eukaryotes), the cell cycle can be divided in two periods: Interphaseduring which the cell grows, accumulating nutrients needed for mitosis and duplicating its DNA. The mitosis (M) phase, during which the cell splits itself into two distinct cells, often called

2、 daughter cells and the final phase, cytokinesis, where the new cell is completely divided. The cell-division cycle is a vital process by which a single-celled fertilized egg develops into a mature organism, as well as the process by which hair, skin, blood cells, and some internal organs are renewe

3、d. Before a cell can enter cell division, it needs to take in nutrients. All of the preparations are done during the interphase. Interphase proceeds in three stages, G1, S, and G2. Cell division operates in a cycle. Therefore, interphase is preceded by the previous cycle of mitosis and cytokinesis.

4、Interphase is also known as preparatory phase, in this stage nucleus and cytosol division does not occur. The cell prepares to divide.InterphaseG1 Phase The first phase within interphase, from the end of the previous M phase until the beginning of DNA synthesis is called G1 (G indicating gap). It is

5、 also called the growth phase. During this phase the biosynthetic activities of the cell, which had been considerably slowed down during M phase, resume at a high rate. This phase is marked by the use of 20 amino acids to form millions of proteins and later on enzymes that are required in S phase, m

6、ainly those needed for DNA replication. Duration of G1 is highly variable, even among different cells of the same species. It is under the control of the p53 gene.S Phase The ensuing S phase starts when DNA synthesis commences; when it is complete, all of the chromosomes have been replicated, i.e.,

7、each chromosome has two (sister) chromatids. Thus, during this phase, the amount of DNA in the cell has effectively doubled, though the ploidy of the cell remains the same. During this phase, synthesis is completed as quickly as possible due to the exposed base pairs being sensitive to external fact

8、ors such as any drugs taken or any mutagens (such as nicotine).G2 Phase The cell then enters the G2 phase, which lasts until the cell enters mitosis. Again, significant biosynthesis occurs during this phase, mainly involving the production of microtubules, which are required during the process of mi

9、tosis. Inhibition of protein synthesis during G2 phase prevents the cell from undergoing mitosis.Mitosis Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets in two nuclei. It is generally followed immediately by cytokinesis, which d

10、ivides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly equal shares of these cellular components. Mitosis and cytokinesis together define the mitotic (M) phase of the cell cycle - the division of the mother cell into two daughter cells, genetically identical to

11、each other and to their parent cell. This accounts for a p p ro x i m a t e l y 1 0 % o f t h e c e l l cycle. Mitosis occurs exclusively in eukaryotic cells, but occurs in different ways in different species. For example, animals undergo an open mitosis, where the nuclear envelope breaks down befor

12、e the chromosomes separate, while fungi such as Aspergillus nidulans and Saccharomyces cerevisiae (yeast) undergo a closed mitosis, where chromosomes divide within an intact cell nucleus. Prokaryotic cells, which lack a nucleus, divide by a process called binary fission.Meiosis Meiosis is a special

13、type of cell division necessary for sexual reproduction in eukaryotes. The cells produced by meiosis are gametes or spores. In many organisms, including all animals and land plants (but not some other groups such as fungi), gametes are called sperm and egg cells. Whilst the process of meiosis bears

14、a number of similarities with the life-cycle cell division process of mitosis, it differs in two important respects: The outcome of meiosis is four (genetically unique) haploid cells, compared with the two (genetically identical) diploid cells produced from mitosis The chromosomes in meiosis undergo

15、 a recombination which shuffles the genes producing a different genetic combination in each gamete, compared with the co-existence of each of the two separate pairs of each chromosome (one received from each parent) in each cell which results from mitosis Glossary Anaphase 后期后期; 分裂后期分裂后期 Cell plate

16、窝眼盘窝眼盘; 细胞板细胞板 Centromere sentr,mi n. 生生 着丝点着丝点, 着丝粒着丝粒 Chalone klun n. 生化生化 抑素抑素 Chromatid krumtid n. 染色分体染色分体 Chromatin krumtin n. 核染质核染质, 染色质染色质Astral adj. 星形的； 星际的 Phycoplast n. 藻质体藻质体; phragmoplast n. 成膜体成膜体; coalesce vi. 联合，合并联合，合并 ;perforate vt. 穿孔于，在穿孔于，在上打眼上打眼; plasmodesmata (复复)胞间连丝胞间连丝 La

17、mella n. 薄层；薄层； 薄片；薄片； 瓣；瓣； 鳃鳃 Terminology n. 专专门名词；门名词； 术语，术术语，术语学；语学； 用辞用辞 Cytokinesis ,saitukaini:sis n. 细胞浆移动细胞浆移动, 原浆移动原浆移动; 胞质分裂胞质分裂 Diploid diplid a. 双重的双重的, 双倍性的双倍性的, 倍数倍数的的 n. 倍数染色体倍数染色体 Haploid hplid n. 生物生物 单倍体单倍体, 仅有一仅有一组染色体的细组染色体的细 a. 单一的单一的 Histone histun n. 生化生化 组蛋白组蛋白 homologous pair

18、 同源染色体对同源染色体对Cytokinesis Cytokinesis, from the greek cyto- (cell) and kinesis (motion, movement), is the process in which the cytoplasm of a single eukaryotic cell is divided to form two daughter cells. It usually initiates during the late stages of mitosis, and sometimes meiosis, splitting a mitoti

19、c cell in two, to ensure that chromosome number is maintained from one generation to the next. Interphase int(:)feiz n. 中间相中间相 (界面界面,相相间的间的)；a. 相间的相间的 Karyotype kritaip n. 生物生物 染色体组染色体组型；核型型；核型 Meiosis maiusis n. 减少；减数分裂减少；减数分裂 Metaphase metfeiz a. 中期中期, 转位期转位期 metaphase plate 赤道板；中期板赤道板；中期板Karyotyp

20、e A karyotype (Greek karyon = kernel, seed or nucleus) is the number and appearance of chromosomes in the nucleus of a eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual organism. Karyotypes describe the number of chromosomes, and what they look

21、 like under a light microscope. Attention is paid to their length, the position of the centromeres, banding pattern, any differences between the sex chromosomes, and any other physical characteristics. The preparation and study of karyotypes is part of cytogenetics. Mitosis mitusis n. 有丝分裂有丝分裂, 间接核分

22、裂间接核分裂 Nucleosome nju:klisum n. 生化生化 核小核小体体 Prophase prufeiz n. （分裂）前期（分裂）前期 Spindle spindl n. 纱锭纱锭, 纺锤纺锤, 轴；轴；v. 变变细长细长 Telophase telfeiz n.（分裂）（分裂） 末期末期 Repository ripzitri n. 贮藏室贮藏室 (博物馆博物馆, 资源丰富地区资源丰富地区) Coil kil n. 卷卷, 骚动；骚动；v. 盘绕盘绕, 卷；卷； n. 【电】线圈【电】线圈, 绕组绕组 Cluster klst n. 串串, 丛丛, 群；群；v. 聚合聚合,

23、 成成串串, 丛生丛生, 使使.聚集聚集 Pictorial pikt:ril a. 绘画的绘画的; n. 画报画报 Immortal im:tl a. 不朽的不朽的; n. 不朽的人物不朽的人物 Metabolism metblizm n. 新陈代谢新陈代谢 Condense kndens v. 浓缩浓缩, 摘要摘要, 缩短缩短 Replicate replikit v. 折叠折叠, 复制复制, 模写模写; n. 八音阶间隔的反复高低音八音阶间隔的反复高低音 Kinetochore kini:tk: n. 生生动粒动粒, 着丝着丝粒粒, 着丝点着丝点 Centriole sentriul n

24、. 生生细胞中心粒细胞中心粒, 中中心体心体 Pinch pint n. 捏捏, 撮撮, 困苦困苦; v. 掐掐, 使使.困困苦苦, 节俭节俭 Progeny prdini n. 子孙子孙(结果结果, 次级粒子次级粒子) Synapsis sinpsis 生生染色体结合染色体结合, 联会联会 Align lain v. 排列排列, 调整调整, 定中心定中心, 校直校直, 使结盟使结盟, 使成一行使成一行 Catastrophic ,ktstrfik a. 悲惨的悲惨的, 灾难灾难的的 Deleterious ,delitiris a. 有害于有害于, 有毒的有毒的 Gamete gmi:t n

25、. 配偶子配偶子 Tetrad tetrd 四位组四位组Synapsis Synapsis (also called syndesis) is the pairing of two homologous chromosomes that occurs during meiosis. It allows matching-up of homologous pairs prior to their segregation, and possible chromosomal crossover between them. Synapsis takes place during prophase I.

26、 When homologous chromosomes synapse, their ends are first attached to the nuclear envelope. These end-membrane complexes then migrate, assisted by the extranuclear cytoskeleton, until matching ends have been paired. Then the intervening regions of the chromosome are brought together, and may be con

27、nected by a protein-RNA complex called the synaptonemal complex. While autosomes undergo synapsis during meiosis, sex chromosomes often remain unpaired.Text Within the nucleus are the chromosomes-tightly coiled strands of DNA and clusters of associated proteins. Each long strand of DNA combines with

28、 histones and nonhistone to make up the substance chromatin.SUMO proteins are similar to ubiquitin, and SUMOylation is directed by an enzymatic cascade analogous to that involved in ubiquitination Karyotypes reveals that in most cells all but sex chromosomes are present as two copies, referred to as

29、 homologous pairs. Organisms whose cells contain two sets of parental chromosomes are called diploid; those with cells containing a single set of parental chromosomes are called haploid. Many cells in multicellular organisms, including animal muscle and nerve cells, either slow the cycle or break out of it altogether. The fourth phase of the cell cycle is M phase, the period of mitosis, during which the replicated chromosomes condensed and move and the cell divides. At the beginning of prophase the chromosomes each consist of two highly condens