2015年武汉大学885分子生物学考研真题(B卷)及详解【圣才出品】

武汉大学2001年攻读硕士学位研究生入学考试试题科目名称:分子生物学科目代码: 477一、解释概念(20分,每个4分)卫星DNA 复制体逆转座子反式激活因子衰减子与衰减作用二、填空(30分,每空1分,请将答案写在答卷上)1. 从病毒到高等生物的研究表明,遗传物质是。

2. 冈崎片段的发现证实了双链DNA的复制,在复制过程中,一条新生链的合成是的,称为链;而另一条链的合成是的,称为链。

3. 大肠菌中有三种DNA聚合酶,其中的pol I的作用是,而pol III的作用是。

pol I和pol III都有的三种活性是、、。

4.由于真核细胞染色体DNA的复制要有一段RNA为引物,因此线状的DN A复制后必须存在着5’端缩短的问题。

已发现有一种端粒蛋白称为,它由构成,可以使单链DNA的5’延长。

5. 对DNA损伤有几种修复系统,其中只有修复系统可以造成DNA变异,与这一系统有关的一套基因平时受到一称为的抑制蛋白所抑制,它发挥抑制作用是结合在一段约20bp长的称为的DNA序列上,当DNA损伤时,另一种蛋白质称为把这种抑制蛋白水解后,修复系统的基因才会被激活。

6.真核细胞中有三种依赖于DNA的RNA聚合酶分别合成不同的RNA,RNA pol I负责合成,RNA pol II负责合成,RNA pol III负责合成。

7.大分子互相作用是分子生物学的重要内容,包括蛋白质之间、蛋白质与DNA或RNA之间的互相作用,蛋白质有四种重要的结构花式与大分子互相作用有关,这些结构花式是, , 。

8. NO是气体小分子信号,它可由脱氨产生,它的作用方式是直接与酶作用使产生cGMP(环式GMP)。

9. 真核mRNA的5’ 端通常有帽子结构,3’ 端有polyA。

在polyA上游有一保守序列称为polyA信号,其序列为。

polyA能提高mRNA的翻译水平是由于:(1) (2) 。

10. G-蛋白关联受体是一类重要的细胞表面受体,它的结构特色是,它发挥信号传递作用的两条途径是途径和途径。

分子生物学武汉大学历年试题（截至2022）●实验设计题●分离基因、鉴定功能——PCR、电泳；敲除、高表达●验证核酸蛋白互作——ESMA、ChIP、DNA足迹法、酵母双杂交●大量表达基因/蛋白——基因工程：强启动子/诱导启动子、高拷贝质粒、偏爱密码子●选择实验原理+扩写●2001●名解●卫星DNA●复制体●逆转座子●反式激活因子●衰减子与衰减作用●问答●说出双链DNA复制起始有关的五种重要的酶或蛋白并简述它们的功能。

(15 分)●简述增强子的特点和性质及作用机制。

(10分)●简述真核RNA聚合酶II的转录起始复合物装配过程和转录起始 (15分)●DNA限制性内切酶EcoRI是人们熟悉的常用内切酶,它是在大肠杆菌(E.coli)R株中发现的,它被广泛用于分子克隆操作和DNA分析。

pUC质粒是常用克隆载体之一,它的多克隆位点上有EcoRI、BamHI、KpnI、HindIII 等酶切点。

假如要你把一段由EcoRI切割产生的外源DNA段克隆到 pUC 质粒中,并把重组质粒转化大肠杆菌R株来扩增,已知条件是所用的R菌株中只有EcoRI一种限制性内切酶,你设计如何做才能确保成功?为什么?(10分)●2002●问答●简述(或绘图说明)真核细胞RNA聚合酶II转录的起始需要哪些基本转录因子及其装配过程(15分)●简述(或绘图说明)色氨酸操纵子弱化的机制(15分)●在讨论基因家庭时经常提到胚胎、胎儿和成体形成的蛋白质,这些述语是指什么现象?可用什么术语来描述这一类基因家族(5分)●你正在进行 Southern blot 分析,并刚刚完成凝胶电泳部分,下一步是将胶浸泡在NaOH溶液中使DNA变性为单链,为了节约时间,你跳过这一步,直接把DNA 从胶上转到硝酸纤维素膜上,你将标记好的探针与膜杂交,却发现放射自显影结果是一片空白,哪里错了呢?(5分)●2003●名解●Domains and motifs 结构域与基序●Alternative splicing 选择性剪接●Reporter genes 报告基因●The PCR cycle 聚合酶链式反应循环●Restriction mapping 限制酶切图谱●Multiple cloning sites 多克隆位点●DNA libraries DNA文库●Proteomics 蛋白质组学●Replicon 复制子●Semi-conservative replication 半保留复制●简答●请列举三种以上蛋白质纯化技术,并说明不同纯化技术的简单原理。

2015年全国硕士研究生入学统一考试教育学专业基础综合（代码311）真题及详解一、单项选择题：l-45小题，每小题2分，共90分。

下列每题给出的四个选项中，只有一个选项是符合题目要求的。

1．夸美纽斯《大教学论》理论论证采用的主要方法是（）。

A．自然类比B．哲学思辨C．经验描述D．科学实验【答案】B【解析】从教育整个历史发展看，教育研究方法的发展大致经历了直觉为主的观察时期；分析为主的方法论时期；形成独立学科时期。

教育研究的发展近代科学产生以后，教育研究进入分析为主的方法论时期。

从夸美纽斯的《大教学论》到新进步主义教育运动的兴起。

这一时期的教育研究方法是同认识论糅合在一起的，采用归纳法和演绎法，重思辨轻实践经验。

A项的自然类比和C项的经验描述属于直觉观察时期；D项的科学实验属于形成独立学科时期。

2～8题略。

9．麦克菲尔的体谅模式中所使用的人际或社会问题情境教材是（）。

A．《学会关心》B．《生命线》C．《中学道德教育》D．《社会与道德教育》【答案】B【解析】《生命线》是由麦克菲尔等人编制的一套独具特色的人际—社会情境问题教材。

这套教材是实施体谅模式的支柱，由《设身处地》《证明规则》《你会怎么办？》三部分组成，循序渐进地向学生呈现越来越复杂的人际与社会情境。

10．教师在长期压力的体验下，会出现情感、态度和行为的衰竭状态，消极应对工作。

这种问题属于（）。

A．职业倦怠B．职业迷茫C．职业逃避D．职业道德失范【答案】A【解析】职业倦怠是指一个人在社会期望值、个体内在的期望值过高而客观实际又达不到预期的目标的情况下所产生的失望的情绪、疲惫的心态的一种心理现象。

教师职业倦怠的典型症状是工作满意度低、工作热情和兴趣的丧失以及情感的疏离和冷漠。

11．《国家中长期教育改革和发展规划纲要（2010-2020）》指出，在普通高中深入推出课程改革，积极开展研究生学习、社区服务和社会实践，建立科学的教育质量评价体系，建立学生发展指导制度。

2013年武汉大学673细胞生物学（B卷）考研真题及详解一、名词翻译与解释（共10小题，每小题3分，共30分）1．necrosis答：necrosis的中文名称是坏死，是指当细胞受到意外损伤，如极端的物理、化学因素或严重的病理性刺激的情况下发生，是有别于细胞凋亡的另一种典型方式。

此时细胞内ATP 浓度已下降到无法维持细胞存活的水平，能量的下降使钠钾泵难以运作，细胞通透性增高，钠、钙、水进入细胞内，钾排除细胞外。

与此同时，糖酵解造成糖原减少，乳酸增多，细胞内酸度增加，内质网损伤，蛋白质合成发生障碍，进一步导致溶酶体膜损伤，各种水解酶被释放到细胞质基质中，使得细胞内其他结构的损伤进一步加重。

2．tight junction答：tight junction的中文名称是紧密连接，是指一种防止细胞内部物质，特别是肠上皮细胞中吸收的营养物质从细胞间隙漏回到肠腔去的屏障，是动物细胞的连接方式之一。

也有防止大分子物质从细胞间隙进入深部组织的作用，紧密连接的结构是相邻细胞的细胞膜在许多线条上互相融合。

这种融合的线称为“密封线”，是两个细胞的膜上蛋白质粒子相对地成排地突出在膜的外侧并互相啮合的结构。

从细胞侧面看，“密封线”是一条微微突起的嵴。

3．endoplasmic reticulum答：endoplasmic reticulum的中文名称是内质网，是指由封闭的管状或扁平囊状膜系统及其包被的腔形成互相沟通的三维网络结构，是真核细胞中最普遍、最多变、适应性最强的细胞器，蛋白质、脂质和糖类的合成基地。

由于内质网的存在，细胞内膜的表面积大为增加，为多种酶特别是多酶体系提供了大面积的结合位点。

分为糙面内质网（rER）和光面内质网（sER）。

4．cell fusion答：cell fusion的中文名称是细胞融合，是指用自然或人工的方法，使两个或更多个不同的细胞融合成一个细胞的过程。

植物细胞由于具有细胞壁，在进行人工诱导融合之前，必须先脱除其细胞壁释放出原生质体才能进行融合；动物细胞可直接用于融合。

武汉大学《分子生物学》复习题库及答案考试复习重点资料（最新版）资料见第二页封面第1页分子生物复习题及答案一、填空题1．病毒ΦX174及M13的遗传物质都是单链DN。

2．IDS病毒的遗传物质是单链RN。

3．X射线分析证明一个完整的DN螺旋延伸长度为3.4nm。

4．氢键负责维持-T间（或G-C间）的亲和力5．天然存在的DN分子形式为右手B型螺旋。

二、选择题（单选或多选）1．证明DN是遗传物质的两个关键性实验是：肺炎球菌在老鼠体内的毒性和T2噬菌体感染大肠杆菌。

这两个实验中主要的论点证据是（C）。

．从被感染的生物体内重新分离得到DN作为疾病的致病剂B．DN突变导致毒性丧失C．生物体汲取的外源DN（而并非蛋白质）改变了其遗传潜能D．DN是不能在生物体间转移的，因此它一定是一种非常保守的分子E．真核心生物、原核生物、病毒的DN能相互混合并彼此替代2．1953年Wtson和Crick提出（）。

．多核苷酸DN链通过氢键连接成一个双螺旋B．DN的复制是半保留的，常常形成亲本-子代双螺旋杂合链C．三个连续的核苷酸代表一个遗传密码D．遗传物质通常是DN而非RNE．分离到回复突变体证明这一突变并非是一个缺失突变3．DN双螺旋的解链或变性打断了互补碱基间的氢键，并因此改变了它们的光汲取特性。

以下哪些是对DN的解链温度的正确描述？（C、D）．哺乳动物DN约为45℃，因此发烧时体温高于42℃是十分危险的B．依赖于-T含量，因为-T含量越高则双链分开所需要的能量越少C．是双链DN中两条单链分开过程中温度变化范围的中间值D．可通过碱基在260nm的特征汲取峰的改变来确定E．就是单链发生断裂（磷酸二酯键断裂）时的温度4．DN的变性（、C、E）。

．包括双螺旋的解链B．可以由低温产生C．是可逆的D．是磷酸二酯键的断裂E．包括氢键的断裂5．在类似RN这样的单链核酸所表现出的“二级结构”中，发夹结构的形成（、D）。

．基于各个片段间的互补，形成反向平行双螺旋B．依赖于-U含量，因为形成的氢键越少则发生碱基配对所需的能量也越少C．仅仅当两配对区段中所有的碱基均互补时才会发生D．同样包括有像G-U这样的不规则碱基配对E．同意存在几个只有提供过量的自由能才能形成碱基对的碱基6．DN分子中的超螺旋（、C、E）。

2012年武汉大学885微生物学考研真题（A卷）及详解一、翻译及名词解释（共10小题，每小题4分，共40分）1．Colonization答：Colonization的中文名称是定植，是指人类的机体与正常菌群或其他各种微生物在长期进化过程中形成的一种共生关系。

定植的微生物必须依靠人体不断供给营养物质才能生长和繁殖，才能进而对人体产生影响（如导致感染）。

但是，人体也在进化过程中发展出一系列防御机制，在正常情况下足以抵御各种微生物的侵袭。

2．Bacteriophage typing答：Bacteriophage typing的中文名称是噬菌体分型。

噬菌体与宿主菌的关系具有高度特异性，即一种噬菌体只能裂解一种和它相应的细菌，因此可用于未知细菌的鉴定和分型。

3．Disinfection答：Disinfection的中文名称是消毒，是指利用温和的物理化学因素抑制病原体繁殖的一种手段。

消毒有物理方法，化学方法及生物方法，但生物方法利用生物因子去除病原体，作用缓慢，而且灭菌不彻底，一般不用于传染病的消毒，故消毒主要应用物理及化学方法。

4．Chemostat答：Chemostat的中文名称是恒化器，是指在整个培养过程中通过保持培养基中某种营养物质的浓度基本恒定的方式，使细菌的比生长速率恒定，生长“不断”进行。

培养基中的某种营养物质通常被作为细菌比生长速率的控制因子。

恒化器连续培养通常用于微生物学的研究，筛选不同的变种。

5．Immunity答：Immunity的中文名称是免疫，是指生物体能够辨认自我与非我，对非我做出反应以保持自身稳定的功能。

免疫是生物在长期进化过程中逐渐发展起来的防御感染和维护机体完整性的重要手段。

宿主免疫防御功能分为非特异性免疫和特异性免疫两大类，它们相辅相成，共同完成抵抗感染保护自身机体的作用，但有时也会造成对机体的病理性损伤。

6．Restriction-modification system答：Restriction-modification system的中文名称是限制修饰系统，是指限制性内切酶和它的“搭档”修饰酶一起组成的系统。

2017年武汉大学885分子生物学考研真题（回忆版）及详解一、名词解释1．Base flipping答：Base flipping中文名称是碱基对打开，是指DNA双链或者RNA双链或者DNA 与RNA杂交双链在解旋酶等酶的作用下氢键断裂，碱基对打开暴露在外环境中的现象。

碱基对打开最早是在1994年在甲基转移酶催化DNA中胞嘧啶甲基化的过程中，通过X射线晶体衍射观察到的现象。

多发生在DNA复制、DNA修复以及RNA转录过程中。

2．RISC答：RISC全称为RNA-induced silencing complex，中文名称为RNA诱导沉默复合物，是指一定数量的外源性双链RNA（dsRNA）进入细胞后，被类似于核糖核酸酶Ⅲ的Dicer酶切割成的小干扰RNA与解旋酶和其他因子结合形成的蛋白质复合物。

RISC在RNA 干扰中起重要作用。

3．EMSA答：EMSA全称为electrophoretic mobility shift assay，中文名称为凝胶迁移实验，是指一种研究DNA结合蛋白和其相关的DNA结合序列相互作用的技术，可用于定性和定量分析，还可用于研究RNA结合蛋白和特定的RNA序列的相互作用。

基本原理是蛋白质与DNA结合后将大大增加相对分子质量，而凝胶电泳中DNA朝正电极移动的距离与其相对分子质量的对数成正比。

因此，没有结合蛋白的DNA片段跑得快，结合蛋白的DNA跑得慢。

4．Amber mutation答：Amber mutation的中文名称为琥珀突变，是指由于一对或几对碱基对的改变而使决定某一氨基酸的密码子变为终止密码子UAG的一种无义突变。

琥珀突变是三种终止密码子突变之一。

这种终止突变会造成肽链合成提前终止，通常也是致死突变。

5．aminoacyl-tRNA synthetase答：aminoacyl-tRNA synthetase中文名称是氨酰-tRNA合成酶，又称氨酰tRNA连接酶，氨基酸活化酶，是指一种合成氨酰tRNA的酶。

武汉大学2015年分子生物学武汉大学2014年分子生物学一.名词解释1、complementDNA2、RNAsplicing3、Gel filtration chromatography4、gene5、snRNP6、OKAZIKIN sequence7、operon8、enhancesome一.简答题1.从分子角度谈谈为什么DNA比RNA更广泛地用作遗传信息的携带者2.试说明中介蛋白在转录调控中的作用原理3.以下是DNA的电泳条带，说明DNA有哪三种拓扑异构构型？设计实验验证该结果。

4.翻译过程需要哪些组分？各自的功能分别是什么三.论述题1.CTD是RNAPOL2的末端结构，说明其结构特点。

它在转录各过程的作用是什么？2.试从产生过程，作用机制和生物学功能几个方面比较miRNA和siRNA的异同点3蛋白质A可以上调蛋白质B的表达水平，说明蛋白A可能在哪些水平发挥作用并设计实验证明。

武汉大学2013年分子生物学一、名词解释（共10小题，每题4分，共40分）1.Ribozyme2.Missense Mutation3.Insulator4.RNA trans-splicing5.Nucleotide excision repair6.Transposon7.Dam methylase8.Spliceosome9.Core promotor10. SNP二、简答题（共5小题，每题10分，共50分）1.真核生物mRNA的5’帽子结构有何生物学功能？其缺失会造成什么后果？2.某一基因开放阅读框中的一个碱基突变会对该基因编码产物产生什么影响？3.请简述真核生物的mRNA和原核生物的mRNA有何不同。

4.请简述Ⅰ型内含子剪切的过程.5.请简述Western blot 的原理和步骤。

三、论述题（共3小题，每题20分，共60分）1.研究基因功能通常是降低或升高基因表达水平，请简要说出三种相关研究方法及原理。

2. mRNA和蛋白质的降解是一个有序的过程，其中microRNA和泛素起了非常重要的作用，请简述microRNA的概念、产生过程、作用机制，或者泛素的概念和蛋白质泛素化的过程。

GLOSSARYAbundance of an mRNA is the average number of molecules per cell.Abundant mRNAs consist of a small number of individual species, each present in a large number of copies per cell.Acceptor splicing site—see right splicing junction.Acentric fragment of a chromosome (generated by breakage) lacks a centromere and is lost cell division.Acrocentric chromosome has the centromere located nearer one end than the other.Active site is the restricted part of a protein to which a substrate binds.Allele is one of several alternative forms of a gene occupying a given locus on a chromosome. Allelic exclusion describes the expression in any particular lymphocyte of only one allele coding for the expressed immunoglobulin.Allosteric control refers to the ability of an interaction at one site of a protein to influence the activity of another site.Alu family is a set of dispersed, related sequences, each～300 bp long, in the human genome. The individual members have Alu cleavage sites at each end (hence the name).Alu-equivalent family is the set of sequences in a mammalian genome that is related to the human Alu family.α-Amanitin is a bicyclic octapeptide derived from the poisonous mushroom Amanita phalloides; it inhibhits transcription by certain eukaryotic RNA polymerases, especially RNA polymerase II.Amber codon is the nucleotide triplet UAG, one of three codons that cause termination of protein synthesis.Amber mutaion describes any change in DNA that creates an amber codon at a site previously occupied by a codon representing an amino acid in a protein.Amber suppressors are mutant genes that code for tRNAs whose anticodons have been altered so that they can respond to UAG codons as well as or instead of to their previous codons.Aminoacyl-tRNA is transfer RNA carrying an amino acid; the covalent linkage is between the NH2group of the amino acid and either the 3’-or-2’-OH group of the terminal base of the tRNA.Aminoacyl-tRNA synthetases are enzymes responsible for covalently linking amino acids to the 2’ or 3’-OH position of tRNA.Amphipathic structures have two surfaces, one hydrophilic and one hydrophobic. Lipids are amphipathic; and some protein regions may form amphipathic; and some protein regions may form amphipathic helices, with one charged face and one neutral face.Amplification refers to the production of additional copies of a chromosomal sequence,1found as intrachromosomal or extrachromoxomal DNA.Anchorage dependence describes the need of normal eukaryotic cells for a surface to attach to in order to grow in culture.Aneuploid chromosome constitution differes from the usal diploid constitution by loss or duplication of chromosomes or chromosomal segments. Annealing is the pairing of complementary single strands of DNA to form a double helix.Antibody is a protein (immunoglobulin) produced by B lymphocyte cells that recognizes a particular foreign ‘antigen,’and thusw triggers the immune res ponse.Anticoding strand of duples DNA is used as a template to direct the synthesis of RNA that is complementary to it.Antigen is any molecule whose entry into an organism provokes synthesis of an antibody (immunoglobulin).Antiparallel strands of the d ouble helix are organized in opposite orientation, so that the 5’ end of one strand is aligened with the 3’ end of the other strand.Antitermination proteins allow RNA polymerase to transcribe through certain terminator sites.Ap endonucleases make incisio ns in DNA on the 5’ side of either apurinic or apyrimidinc sites.Apoinducer is a protein that binds to DNA to switch on transcription by RNA polymerase. Archebacteria comprise a minor line of prokaryotes, and may have introns in the genome. Ascus of a fungus contains a tetrad or octad of the (haploid) spores, representhing the products of a sihngle meiosis.att sties are the loci on a phage and the bacterial chromosome at which recombination integrates the phage into. or excises it from , the bacterial chromosome.Attenuation describes the regulation of termination of transcription that is involved in controlling the expression of some bacterial operons.Attenuato r is the terminator sequence at which attenuatioj occurs.Autogenous conhtrol describes the action of a gene product that either inhibits (negative autogenous control) or activates (positive autogenous control) expression of the gene coding for it.Autonomous controlling element in maize is an active transposon with the ability to transpose (cf nonautonomous controlling element).Autoradiography detects radioactively labeled molecules by their effect in creating an image on pholtographic film.Autosomes are all the chromosomes except the sex chromosomes; a diploid cell has two copies of each autosome.Blymphocytes (or B cells) are the cells responsible for synthesizing antibodies.2Backcross is another (earlier) term for a testcross.Back mutation reverses the effect of a mutation that hand inactivated a gene; thus it restores wild type.Bacteriophages are viruses that infect bacteria; often abbreviated as phages.Balbaini ring is an extremely large puff at a band of a polytene chromosome.Bands of polytene chromosomes are visible as dense regions that contain the majority of DNA;bands of normal chromosomes are relatively much larger and are generated in the form of regions that retain a stain on certain chemical treatments.Base pair (bp) is a partnership of A with T or of C with G in a DNA double helix; other pairs can be formed in RNA under certain circumstances.Bidirectional replication is accomplished when two replication forks move away from the same origin in different directions.Bivalent is the structure containing all four chromatids (two representing each homologue) at the start of meiosis.Blastoderm is a stage of insect embryogenesis in which a layer of nuclei or cells around the embryo surround an internal mass of yolk.Blocked reading frame cannot be translated into protein because it is interrupted by termination codons.Blunt-end ligation is a reaction that joins two DNA duplex molecules directly at their ends. bp is an abbreviation for base pairs; distance along DNA is measured in bp.Branch migration describes the ability of a DNA strand partially paired with its complement in a duplex to extend its pairing by displacing the resident strand with which it is homologous. Breackage and reunion describes the mode of genetic recombination, in which two DNA duplex molecules are broken at corresponding points and then rejoined crosswise (involving formation of a length of heteroduplex DNA around the site of joining).Buoyant desity measures the ability of a substance to float in some standard fluid, for example, CsCl.C banding is a technique for generating stained regions around centromeres.C genes code for the constant regions of immunoglobulin protein chains.C value is the total amount of DNA in a haploid genome.CAAT box is part of a conserved sequence located upstream of the startpoints of eukaryotic transcription units; it is recognized by a large group of transcription factors.Cap is the structure at the 5’ end of eukaryotic mRNA, introduced after transcripton by linking the terminal phosphate of 5’ GTP to the terminal base of the mRNA. The added G (and sometimes some other bases) are methylated, giving a structure of the form 7Me G5’ppp 5’Np…3CAP(CRP)is a positive regulator protein activated by cyclic AMP. It is needed for RNA polymerase to initiate transcription of certain (catabolitesensitive) operons of E. coli.Capsid is the external protein coat of a virus particle.Catabolite repression describes the decreased expression of many bacterial operons that results from addition of glucose. It is caused by a decrease in the level of cyclic AMP, which in turn inactivates the CAP regulator.cDNA is a single-stranded DNA complementary to an RNA, synthesized from it by reverse transcription in vitro.cDNA clone is a duplex DNA sequence representing an RNA, carried in a cloning vector. Cell cycle is the period from one division to the next.Cell hybrid is a somatic cell containing chromosomes derived from parental cells of different species (e.g. a man-mouse somatic cell hybrid), generating by fusing the cells to form a heterokaryon in which the nuclei subsequently fused.Centrioles are small hollow cylinders consisting of microtubules that become located near the poles during mitosis. They reside within the centrosomes.Centromere is a constricted region of a chromosome that includes the site of attachment to the mitotic or meiotic spindle (see also kinetochore).Centrosomes are the regions from which microtubules are organized at the poles of a mitotic cell. In animal cells, each centrosome contains a pair of centrioles surrounded by a dense amorphous region to which the microtubules attach. See also MTOC.Molecular chaperone is a protein that is needed for the assembly or proper folding of some other protein, but which is not itself a component of the target complex.Chemical complexity is the amount of a DNA component measured by chemical assay.Chi sequence is an octamer that provides a hotspot for RecA-mediated genetic recombination in E. coli.Chi structure is a joint between two duplex molecules of DNA revealed by cleaving an intermediate of two joined circles to generate linear ends in each circle. It resembles a Greek chi in outline, hence the name.Chiasma (pl. chiasmata)is a site at which two homologous chromosomes appear to have exchanged material during meiosis.Chromatids are the copies of a chromosome produced by replication. The name is usually used to describe them in the period before they separate at the subsequent cell division. Chromatin is the complex of DNA and protein in the nucleus of the interphase cell. Individual chromosomes cannot be distinguished in it .It was originally recognized by its reaction with stains specific for DNA.Chromocenter is an aggregate of heterochromatin from different chromosomes. Chromomeres are densely staining granules visible in chromosomes under certain conditions, especially early in meiosis, when a chromosome may appear to consist of a series of4chromomeres.Chromosome is a discrete unit of the genome carrying many genes. Each chromosome counsists of a very long molecule of duplex DNA and an approximately equal mass of proteins. It is visible as a morphological entity only during cell division.Chromosome walking describes the sequential isolation of clones carrying overlapping sequences of DNA, allowing large regions of the chromosome to be spanned. Walking is often performed in order to reach a particular locus of interest.cis-acting locus affects the activity only of DNA sequences on its own molecule of DNA; this property usually implies that the locus does not code for protein.cis-acting protein has the exceptional property of acting only on the molecule of DNA from which it was expressed.cis configuration describes two sites on the same molecule of DNA.cis/trans test assays the effect of relative configuration on expression of two mutations. In a double heterozygote, two mutations in the same gene show mutant phenotype in trans configuration, wild-type in cis configuration.Cistron is the geneti unit defined by the cis/trans test; equivalent to gene ib comprising a unit of DNA representing a protein.Class switching is a change in the expression of the c cregion of an immunoglobulin heavy chain during lymphocyte differentiation.Clone describes a large number of cells or molecules identical with a single ancestral cell or molecule.Cloning vector is a plasmid or phage that is used to ‘carry’ inserted foreign DNA for the purposes of producing more material or a protein product.Closed reading frame contains termination codons that prevent its translation into protein. Coated vesicles are vesicles whose membrane has on its surface a layer of the protein clathrin.Coconversion is the simultaneous correction of two sites during gene conversion.Coding strand of DNA has the same sequence as mRNA.Codominant alleles both contribute to the phenotype; neither is dominant over the other. Coevolution —see concerted evolution.Cognate tRNAs are those recognized by a particular aminoacy-tRNA synthetase. Coointegrate structure is produced by fusion of two replicons, one originally possessing a transposon, the other lacking it; the cointegrate has copies of the transposon present at both junctions of the replicons, oriented as directrepeats.Cold-sensitive mutant is defective at low temperature but functional at normal temlperature. Colony hybridization is a technique for using in situ hybridization to identify bacteria carrying chimeric vectors whose inserted DNA is homologous with some particular sequence. Compatibility group of plasmids contains members unable to coexist in the same bacterial5cell.Complementation refers to the ability of independent (nonallelic)genes to provide diffusible products that produce wild phenotype when two mutants are tested in trans configuration in a heterozygote.In vitro complementation assay consists of identifying a component of a wid-type cell that can confer activity on an extract prepared from a mutant cell. The assay identifies the component rendered inactive by the mutation.Complementation group is a series of mutations unable to complement when tested in pairwise combinations in trans; defines a genetic unit (the cistron) that might better be called a noncomplex mentation group.Complex locus (of D. melanogaster) has genetic properties inconsistent with the function of a gene representing a single protein. Complex loci are usually very large (>100kb) at the molecular level.Complexity is the total length of different sequences of DNA present in a given preparation. Compostie transposons have a central region flanked on each side by insertion sequences, either or both of which may enable the entire element to transpose.Concatemer of DNA consists of a series of unit genomes repeated in tandem. Concatenated circles of DNA are interlocked like rings one a chain.Concerted evolution describes the ability of two related genes to evolve together as though constituting a single locus.Condensation reaction is one in which a covalent bond is formed with loss of a water molecule, as in the addition of an amino acid to a polypeptide chain.Conditional lethal mlutations kill a cell or virus under certain (nonpermissive) conditions, but allow it to survive under other (permissive) conditions.Conjugation describes ‘mathing’ between two bacterial cells, when (part of ) the chromosome is transferred from one to the other.Consensus sequence is an idealized sequence in which each position represents the base most often found when many actual sequences are compared.Conservative recombination involves breakage and reunion of preexisting strands of DNA without any synthesis of new stretches of DNA.Conservative transposition refers to the movement of large elements, originally classified as transposons, but now considered to be episomes. The mechanism of movement resembles that of phage lambda.Constant regions of immunoglobulins are coded by C genes and are the parts of the chain that vary least. Those of heavy chains identify the type of immunoglobulin.Constitutive genes are expressed as a function of the interaction of RNA polymerase with the promoter, without additional regulation; sometimes also called household genes in the context of describing functions expressed in all cells at a low level.67Constitutive heterochromatin describes the inert state of permanently nonexpressed sequences, usually satellite DNA.Constitutive mutations cause genes that usually are regulated to be expressed without regulation.Contractile ring is a ring of actin filaments that forms around the equator at the end of mitosis and is responsible for pinching the daughter cells apart.Controlling elements of maize are transposable units originally identified solely by their genetic properties. They may be autonomous (able to transpose independently) or nonautonomous (able to element).Coordinate regulation refers to the common control of a group of genes.Cordycepin is 3’ deoxyadenosine, an inhibitor of poly adenylation of RNA.Core DNA is the 14.6 bp of DNA contained on a core particle.Core particle is a digestion product of the nucleosome that retains the histone octamer and has 14.6 bp of DNA; its structure appears similar to that of the nucleosome itself.Corepressor is a small molecule that triggers repression of transcription by binding to a regulator protein.Cosmids are plasmids into which phage lambda cos sites have been inserted; as a result, the plasmid DNA can be packaged in vitro in the phage coat.Cot is the product of DNA concentration and time of incubation in a reassociation reaction. Cot 21 is the Cot required to proceed to half completion of the reaction; it is directlyproportional to the unique length of reassociating DNA.Cotransfection is the simultaneous transfection of two markers.Crossing-over describes the reciprocal exchange of material between chromosomes that occurs during meiosis and is responsible for genetic recombination.Crossover fixation refers to a possible consequence of unequal crossing-over that allows a mutation in one member of a tandem cluster to spread through the whole cluster (or to be eliminated).Cruciform is the structure produced at inverted repeats of DNA if the repeated sequence pairs with its complement on the same strand (instead of with its regular partner in the other strand of the duplex).Cryptic satellite is a satellite DNA sequence not identified as such by a separate peak on a density gradient; that is, it remains present in main-band DNA.ctDNA is chloroplast DNA.Cyclic AMP (cAMP) is a molecule of AMP in which the phosphate group is joined to both the 3’ and 5’ positions of the ribose; its binding activates the CAP, a postive regulator of prokaryotic transcription.Cyclins are proteins that accumulate continuously throughout the cell cycle and are thendestroyed by proteolysis during mitosis. (see also MPF).Cytokinesis is the final process involved in separation and movement apart of daughter cells at the end of mitosis.Cytological hybridization—see in situ hybridization.Cytoplasm describes the material between the plasma membrane and the nucleus. Cytoplasmic inheritance is a property of genes located in mitochondria or chloroplasts (or possibly other extranuclear organelles).Cytoplasmic protein synthesis is the ranslation of mRNAs representing nuclear genes; it occurs via ribosomes attached to the cytoskeleton.Cytoskeleton consists of networks of fibers in the cytoplasm of the eukaryotic cell.Cytosol describes the general volume of cytoplasm in which organelles ( such as the mitochondria ) are located.D loop is a region within mitochondrial DNA in which a short stretch of RNA is paired with one strand of DNA, displacing the orignal partner DNA strand in this region. The same term is used also to describe the displacement of a region of one strand of duplex DNA byu a single-stranded invader in the reaction catalyzed by RecA protein.Degeneracy in the genetic code refers to the lack of an effect of many changes in the third base of the codon on the amino acid that is represented.Deletions are generated by removal of a sequence of DNA, the regions on either side being joined together.Denaturation of DNA or RNA describes its conversion from the double-stranded to the singlestranded state; separation of the strands is most often accomplished by heating. Denaturation of protein describes its conversion from the physiological conformation to some other (inactive) conformation.Derepressed state describes a gene that is turned on. It is synonymous with induced when describing the normal state of a gene; it has the same meaning as constitutive in describing the effect of mutation.Dicentric chromosome is the product of fusing two chromosome fragments, each of which has a centromere. It is unstable and may be broken when the two centromeres are pulled to opposite poles in mitosis.Diploid set of chromosomes contains two copies of each autosome and two sex chromosome. Direct repeats are identical (or related) sequences present in two or more copies in the same orientation in the same molecule of DNA; they aer not necessarily adjacent.Discontinuous replication refers to the synthesis of DNA in short (Okazaki) fragments that are later joined into a continuous strand.Disjunction describes the movement of members of a chromosome pair to opposite poles during cell division. At mitosis and the second meiotic division, disjunction applies to sister8chromatids; at first meiotic division it applies to sister chromatid pairs.Divergence is the percent difference in nucleotide sequence between two related DNA sequences or in amino acid sequences between two proteins.Divergent transcription refers to the intitiation of transcription at two promoters facing in the opposite direction, so that transcription proceeds away in both directions from a central region.dna mutants of bacteria are temperature-sensitive; they cannot synthesize DNA at 42℃, but can do so at 37℃.DNAase is an enzyme that attacks bonds in DNA.DNA-driven bybridization involves the reaction of an excess of DNA with RNA.DNA polymerase is an enzyme that synthesizes a daughter strand(s) of DNA (under direction from a DNA template). May be involved in repair or replication.DNA replicase is a DNA-synthesizing enzyme required specifically for replication.Domain of a chromosome may refer either to a discrete structural entity defined as a region within which supercoiling is independent of other domains; or to an extensive region including an expressed gene that has heightened sensitivity to degradation by the enzyme DNAase I.Domain of a protein is a discrete continuous part of the amino acid sequence that can be equated with a particular function.Dominant allele determines the phenotype displayed in a heterozygote with another (recessive) allele.Donor splicing site—see left splicing junction.Down promoter mutations decrease the frequency of initiaton of transcription. Downstream identifies sequences proceeding farther in the direction of expression, for example, the conding region is downstream of the initiation condon.Early development refers to the period of a phage infection before the start of DNA replication.Extopic expression describes the expression of a gene in a tissue in which it is not usually expressed; for example, in a transgenic animal.Elongation factors (EF in prokaryotes, eEF in eukaryotes) are proteins that associate with ribosomes cyclically, during addition of each amino acid to the polypeptide chain.End labeling describes the addition of a radioactively labeled group to one end (5’ or 3’) of a DNA strand.End-product inhibition describes the ability of a product of a metabolic pathway to inhibit the activity of an enzyme that catalyzes an early step in the pathway.Endocytosis is a process by which proteins at the surface of the cell are internalized, being transported into the cell within membranous vesicles.9Endocytic vesicles are membranous particles that transport proteins through endocytosis; also known as clathrin-coated vesicles.Endonucleases cleave bonds within a nucleic acid chain; they may be specific for RNA or for singlestranded of double-stranded DNA.Endoplasmic reticulum is a highly convoluted sheet of membranes, extending from the outer layer of the nuclear envelope into the cytoplasm.Enhancer element is a cis-acting sequence that increases the utilization of (some) eukaryotic promoters, and can function in either orientation and in any location (upstream or downstream) relative to the promoter.Envelopes surround some organelles (for example , nucleus or mitochondrion) and consist of concentric membranes, each membrane consisting of the usual lipid bilayer.Epigenetic changes influrence the phenotype without altering the genotype. They consist of changes in the properties of a cell that are inherited but that do not represent a change in genetic information.Episome is a plasmid able to integrate into bacterial DNA.Epistasis describes a situation in which expression of one gene wipes out the phenotypic effects of another gene.Essential gene is one whose deletions is lethal to the organism (see also lethal locus). Established cell lines consist of eukaryotic cells that have been adapted to indefinite growth in culture (they are said to be immortalized).Eubacteria comprise the major line of prokaryotes.Euchromatin comprises all of the genome in the interphase nucleus except for the heterochromatin.Evolutionary clock is defined by the rate at which mutations accumulate in a given gene. Excision-repair systems remove a single-stranded sequence of DNA containing damaged or mispaired bases and replace it in the duplex by synthesizing a sequence complementary to the remaining strand.Exocytosis is the process of secreting proteins from a cell into the medium, by transport in membranous vesicles from the endoplasmic reticulum, through the Golgi, to storage vesicles, and finally (upon a regulatory signal) through the plasma membrane.Exocytic vesicles (also secretory vesicles) are membranous particles that transport and store proteins during excytosis.Exon is any segment of an interrupted gene that is represented in the mature RNA product. Exonucleases cleave nucleotides one at a time from the end of a polynucleotide chain; they may be specific for either the 5’ or 3’ end of DNA or RNA.Expression vector is a cloning vector desined so that a coding sequence inserted at a particular site will be transcribed and translated into protein.Extranuclear genes reside outside the nucleus in organelles such as mitochondria and10chloroplasts.F factor is a bacterial sex or fertility plasmid.F1 generation is the first generation produced by crossing two parental (homozygous) lines. Facultative heterochromatin describes the inert state of sequences that also exist in active copies—for example, one mammalian X chromosome in females.Fast component of a reassociation reaction is the first to reature and contains highly repetitive DNA.Fate map is a map of an embryo showing the adult tissues that will develop from the descendants of cells that occupy particular regions of the embryo.Figure eight describes two circles of DNA linked together by a recombination event that has not yet been completed.Filter hybridization is performed by incubating a deatured DNA preparation immobilized on a nitrocellulose filter with a solution of radioactively labeled RNA or DNA.Fingerprint of DNA is a pattern of polymorphic restriction fragments that differ between individual genomes.Fingerprint of a protein is the pattern of fragments (usually resolved on a two dimensional electrophoretic gel) generated by cleavage with an enzyme such as trypsin.Fluidity is a property of membranes; it indicates the ability of lipids to move laterally within their particular monolayer.Focus formation describes the ability of transformed eukaryotic cells to grow in dense clusters, piled up on one another.Focus forming unit (ffu) is a quantitative measure of forcus formation.Foldback DNA consists of inverted repeats that have renatured by intrastrand reassociation of denatured DNA.Foot printing is a technique for identifying the site on DNA bound by some protein by virtue of the protection of bonds in this region against attack by nucleases.Forward mutations inatctivate a wild-type gene.Founder effect refers to the presence in a population of many individuals all with the same chromosome (or region of a chromosome) derived from a single ancestor.Frameshift mutations arise by deletions or insertions that are not a multiple of 3bp; they change the frame in which triplets are translated into protein.G banding is a technique that generates a striated pattern in metaphase chromosomes that distinguishes the members of a haploid set.G1 is the period of the eukaryotic cell cycle between the last mitosis and the start of DNA replication.G2 is the period of the eukaryotic cell cycle between the end of DNA replication and the start11。