分子生物学期末考试复习内容-2011

1、Section AProkaryotes：原核生物，没有成形的细胞核或线粒体的一类单细胞生物，the simplest living cellsEukaryotes：真核生物，所有单细胞或多细胞的、其细胞具有细胞核的生物的总称；denfined by their possension of membrane-enclosed organelles with specialized metabolic functions.Differentiation:分化，生物体发育过程中细胞和组织的结构和功能的变化；in most multicellular eukaryotes, groups of ce

2、lls differentiate during development of the organism to provide specialized functionsGlycerides (甘油酯): 通常指由甘油和脂肪酸（包括饱和脂肪酸和不饱和脂肪酸）经酯化所生成的酯类, 是中性脂肪，是血脂肪的成分之一，扮演著贮存与输送的角色Triglycerides(甘油三酯):是长链脂肪酸和甘油形成的脂肪分子。是人体内含量最多的脂类，大部分组织均可以利用甘油三酯分解产物供给能量，同时肝脏、脂肪等组织还可以进行甘油三酯的合成，在脂肪组织中贮存Polysaccharides:多糖，单糖以糖苷键工价连接的

3、聚合体，其功能主要是作为营养糖源或结构组分。Polymers of simple sugars covalently linked by glycosidic bonds,as untritional sugar stores and as structural materialsGlycoproteins:糖蛋白，既含有蛋白质又含有糖，糖基化是蛋白质翻译后修饰的通常形式。Contain both protein and carbohydrate components;glycosylation is the commonest form of post-translational modif

4、ication of proteinsChromatin:染色质是构成真核生物染色体的原件，是一个由大约等量的DNA与小分子的碱性蛋白质所组成的脱氧核蛋白复合体，the material from which eukaryotic chromosomes are made,is a deoxyribinucleoprotein complex made up of roughyl equal amounts of DNA and small,basic proteins called histonesBiomembranes:生物膜，将磷脂与鞘脂置于水中，会自发地形成一个极性基团在外、非极性烃

5、链在内的脂双分子层，when placed in an aqueous environment,phospholipids and sphingolpids naturally form a lipid bilayer with the polar groups on the outside and the nonpolar hydrocarbon chains on the inside.Hydrogen bonds:氢键，在供体基因的一个共价结合的氢原子和受体基因上一对非成键电子之间形成，form between a covalently bonded hydrogen atom on a

6、 donnor group and a pair of nonbonding electrons on an acceptor groupvan der Waals forces:范德华力，电中性分子间的非共价结合的统称，noncovalent associations between electrically neutral monleculesHydrophobic interaction:疏水相互作用，指水介质中球状蛋白质的折叠总是倾向于把疏水残基埋藏在分子内部的现象，是蛋白质-蛋白质和蛋白质-脂类的相互作用以及核酸结构中的主要稳定力，a major sabilizing force i

7、n protein-protein and protein-lipid interactions and in nucleic acidsphospholipid molecule:磷脂分子，由两分子脂肪酸和一分子磷酸以酯键与甘油相结合，是膜的主要成分，consist of glycerol esterifide to two fatty acids and phosphoric acid and contained in memvraneshydrophilic polar head group and a hydrophobic tail. 亲水性极性头部和疏水尾部，磷脂分子有亲水性的极性

8、头组和疏水尾巴，亲水性头部朝向水相，疏水性尾部避水彼此聚集，形成双分子层，A phospholipid molecule consists of a hydrophilic polar head group and a hydrophobic tail，When placed in water, the hydrophilic heads tend to face water and the hydrophobic tails are forced to stick together, forming a lipid bilayer.Lipoproteins:脂蛋白，与蛋白质结合在一起形成的脂

9、质-蛋白质复合物，is a biochemical assembly that contains both proteins and lipids water-bound to the proteinsDensity gradients:密度梯度，包括速度区带离心和等密度离心。速度区带离心，混合物被加入离心管中预先铺好的适当介质的浓度（形成密度）梯度顶层。通过离心，不同成分将根据它们的沉降系数以不同的速度下沉并形成相互分离的带或区带。建立介质密度梯度的目的是为了阻碍分离后组分的扩散混合，并且确保组分的线性分离速率。等密度离心，密度梯度延伸至比混合物中的一个或多个组分大一些的密度，因此这些组分在

10、等于它们自己密度的点达到平衡并且停止移动，在这种情况下，密度梯度可以预先建立，然后将样品加在上层，也可以是样品与梯度物质混合在一起离心时自动形成。Functions of Membrane:膜的功能，膜上有膜蛋白，决定了膜的功能：作为激素和神经递质等信号分子的受体；作为在吸收物质前降解细胞外分子所需的酶；作为选择性转运小分子、极性离子和分子的孔或通道；作为细胞与细胞相互作用的介质（主要是糖蛋白）。Receptors for signaling molecules such as hormons and neurotransmitters; enzymes for degrading extra

11、cellular molecules before uptake of the products; pores or channels for the selective transport of small, polar ions and molecules; mediators of cell-cell interactions (mainly glycoproteins).Section BAmino acids:氨基酸，有一个与质子、氨基、羧基相连的手性-碳原子和具有不同的理化特性的侧链，在溶液中表现为两性离子，have a chiral -carbon atom linked to

12、a proton, amino and carboxyl groups, and a specific side chain which confers diifferent physical and chemical properties, behave as zwitterions in solution.Acidicbasicpolarnonpolararomatic amino acids:(酸性aa：Asp, Glu; 碱性aa：Lys, Arg)(中性：His)带点; 极性aa：Ser, Thr, Asn, Gln, Cys; 非极性aa: Gly, Ala, Val, Leu,

13、Ile, Met, Pro; 芳香族aa: Phe, Tyr, TrpPrimary structure of protein:蛋白质的一级结构，多肽中从N端到C端的氨基酸序列，the sequence of amino acids from the N to the C terminus-helix: 螺旋，蛋白质中常见的二级结构，常在球蛋白和一些纤维蛋白中发现，右手螺旋每圈友3.6个氨基酸，在肽链的N-H与相隔三个残基的C=O基团间形成氢键以稳定其整体结构，the best known secondary structure in proteins, often found in glob

14、ular proteins and in some fibrous proteins, the right-handed -helix has 3.6 amino acids per turn and is stbbilized by hydrogen bonds between peptid N-H and C=O groups three residues apart-sheet: 折叠，蛋白质的二级结构，坚硬牢固，是重要的结构蛋白，由肽链N-H和C=O基团与肽链上另一段互补的基团间以氢键维系，the secondary structure in proteins, strong and

15、rigid, important in structural proteins, formed by hydrogen bonding of the peptide bond N-H and C=O groups to the complementary groups of another section of the polypeptide chainParallel -sheet: 正向平行的折叠，多肽链中的几个片段走向相同，the sections of polypeptide chain run in the same directionAntiparallel -sheet: 反向平

16、行的折叠，多肽链中的片段走向为N端C端和C端N端，the section of polypeptide chain alternate NC and CNprimary structure: 一级结构，多肽中从N端到C端的氨基酸序列，the sequence of amino acids from the N to the C terminussecondary structure: 二级结构，多肽链借助氢键排列自己特有的螺旋和折叠片断，polypeptide chains are able to fold into a number of regular structures which a

17、re held together by hydrogen bondsTertiary structure: 三级结构，不同的二级结构区域和连接区的组合折叠成一个确定的三级结构， the different sections of secondary structures and connecting regions fold into a well-defined tertiary structureQuaternary structure: 四级结构，指数条具有独立的三级结构的多肽链通过非共价键相互连接而成的聚合体结构，A structural level wherein several p

18、roteins or polypeptide subunits interact through non-covalent bonds to form one functional protein complexDomains：结构域，是在同一多肽中有限的高度有序结构片段相连而成，在真核生物中常由基因中的不连续部分(称为外显子)来编码，connected by sections with limited higher order structure within the same polypeptide, often encoded by discrete parts of genes cal

19、led exons in eukaryotesMotif：基序，二级结构元件组合或在蛋白质家族的相关成员中常发现的氨基酸序列，是在不相关蛋白凑在一起时实现结构-功能统一的最佳解决方案，are groupings of secondary structural elements or amino acid sequences often found in related members of protein families, represent the best solution to a structural-functional requirement that has been arri

20、ved at independently in unrelated proteinsProtein families：蛋白质家族，通过基因复制和随后的新基因趋异进化产生，不同物质的具有相同功能、承担相同生化角色的蛋白质家族成员为直向同源（定向进化同源），进化不同但功能类似的蛋白质为共生同源（平行进化同源），不同生物体的一个蛋白质家族直向同源成员间氨基酸序列的相似程度取决于两个生物体从共同祖先歧化的时间以及该序列的保守性对蛋白质功能的重要性，arise through gene duplication and subsequent divergent evolution of the new g

21、enes, family members in different species theat have retained the same function and carry out the same biochemical role are orthologs while those that have evolved different, but often related functions are paralogs, the degree of similarity between the amino acid sequences of orthologous members of

22、 a protein family in different organisms depengds on how long ago the two organisms diverged from their common ancestor and on how important conservation of the sequence is for the function of the proteinProtein functions: 蛋白质功能，酶，可以将生化反应速度提高几个数量级，enzymes, can enhance the rate of biochemical reactio

23、ns by several orders of magnitude; 信号传递，细胞膜上的受体蛋白质可以与来自细胞外介质的配体结合，通过最终的构象改变，在细胞内启动对应于配体的反应，signaling, receptor proteins in cell membranes can bind ligands from the extracellular medium and, by virtue of the resulting conformational change, initiate reactions within the cell in response to that ligan

24、d; 转运与储存，许多分子和离子都以蛋白质结合形式转运和储存，这样在需要用它们之前，可以增加溶解性、减小反应活性，transport and storage, molecules and ions are transported and stored in a protein-biund form, can enhance solubility and reduce reactivity until they are requiredThe principal properties of proteins used for purification:用于纯化蛋白质的主要特性，有大小、电荷、疏水

25、性和对其他分子的亲和性，大小（凝胶过滤层析），电荷（离子交换层析、等电聚焦、电泳），疏水性（疏水作用），亲和性（亲和层析），重组技术（过量表达重组蛋白质），size, charge, hydrophobicity, and affinity for other molecules, size(Gel filtration chromatography), charge( ion-exchange chromatoraphy, isoelectric focusing, electophoresis ), hydrophobicity (hydrophobic interaction chrom

26、atography), affinity(affinity chromatography),recombinant techniques(overexpression of the protein greatly)globular proteins:球蛋白，紧凑的、近似球形的、含折叠紧密的多肽链，多溶于水，典型的球蛋白含有能特异识别和结合其他化合物的凹陷或裂隙部位，能在其中找到螺旋fibrous proteins：纤维蛋白，含有呈现相同二级结构的多肽链，不溶于水，许多纤维蛋白紧密结合，为单个细胞或整个生物体提供机械强度，起着保护结构的作用。Section C:Nucleosides：核苷，由碱

27、基共价结合于戊糖分子的1位构成，RNA中的戊糖为核糖，构成核糖核苷，DNA中的戊糖为2-脱氧核糖，形成2-脱氧核糖核苷。碱基+糖分子=核苷。A base covalently bonded to the 1-position of a pentose sugar molecule, in RNA the sugar is ribose and the compounds are ribonucleosdes, in DNA the sugar is 2-deoxyribose and the compounds are 2-deoxyribonucleosids. Base + sugar =

28、 nucleosideNucleotide: 核苷酸，由一个或多个磷酸基团共价结合到核苷的3位、5为或2位（RNA）形成，碱基+糖分子+磷酸分子=核苷酸。RNA（NTP）, DNA（dNTP）。Nucleosides with one or more phosphate groups covalently bound to the 3-, 5- or, 2- in ribonucleotides, base + sugar + phosphate = nucleotide.Hypochromicity (减色性):减色效应，双链DNA相对于单链DNA吸收值减少的现象，double-strand

29、ed DNA is hypochromic with respect to single-stranded DNA. （越多链，吸收值越小）Hyperchromicity (增色性)：增色效应，与减色效应相反，ssDNA相当于dsDNA是增色的，ssDNA is hyperchromic with respect to dsDNA.Melting temperature (Tm): 溶解温度/解链温度，DNA分子内50%的双链结构被打开, 另外50%的还保持着双螺旋结构时的温度, the temperature at which 50% of the DNA molecules from a

30、stable double helix and the other 50% have been separated to single strand molecules.Linker number (Lk, 连接数): 自然条件下，DNA通常以闭环形式存在，即两条单链均为环状且相互连在一起，相互连接的数目称为连接数，DNA frequently occurs in nature as closed-circular molecules, where the two single strands are each circular and linked together, the number

31、of links is known as Lk.l Intramolecular hydrogen bonding and base stacking are the forces for DNA secondary and tertiary structure.分子内氢键和碱基堆积是DNA二、三级结构的力量l Hydrogen bonding does not normally contribute the DNA stability, DNA Stability lies in the stacking interactions between base pairs. 氢键一般对DNA的稳

32、定没有作用，DNA的稳定决定于碱基对之间的堆积作用l Hydrogen bonding contributes to specific structures of DNA and protein, such as -helix, -sheet, DNA double helix, RNA secondary structure.氢键对DNA和蛋白质的特殊结构有作用，例如螺旋，折叠，DNA双螺旋，RNA的二级结构l Stacking interaction/hydrophobic interaction between aromatic base pairs/bases contribute t

33、o the stability of nucleic acids.芳香族的碱基对/碱基间的堆积作用/疏水作用有助于核酸的稳定l Properties of nucleic acids: strong acid and high temperature (such as perchloric acid HClO4 +100), nucleic Acids will be completely hydrolyzed to bases, riboses / deoxyribose, and phosphate.核酸的性质：在强酸性和高温下（如在高氯酸HClO4 +100），核酸会完全水解为碱基，核糖

34、/脱氧核糖和磷酸l When nucleic acids is at the condition of moderate acid (such as pH 3-4), glycosylic bonds attaching purine (A and G) bases to the ribose ring are broken into apurinic nucleic acids. 当核酸在中度的酸性条件下（如pH3-4），连接嘌呤和核糖的糖苷键会断开变成脱嘌呤核酸l High pH denatures DNA and RNA by altering the tautomeric (互变异构)

35、 state of the bases and disrupting specific hydrogen bonding 强碱条件下DNA和RNA因其碱基的互变异构态的改变以及特异氢键被破坏而变性l RNA can be hydrolyzed at higher pH by participation of 2-OH groups in intramolecular cleavage of the phosphodiester backbone.RNA在强碱下水解，2-OH参与磷酸二酯键骨架的分子内裂解l The conformation (geometry) of the DNA can b

36、e altered while the linking number remains constant. 当连接数不变是，DNA分子的（几何）构象可以发生改变l The topological change (DLk) in supercoiling of a DNA molecule is partitioned into a conformational change of twist (DTw )and/or a change of writhe (DWr).超螺旋的DNA分子的拓扑变化(DLk)可以分为构象变为缠绕(DTw )和/或扭曲(DWr)l According to the r

37、atio of OD260/280, how to evaluate the purity of DNA or RNA samples? 根据OD260/280的比值，如何去估计DNA或RNA样品的纯度？OD260/280中，纯dsDNA为1.8，纯RNA为2.0，纯蛋白质为0.5左右。大于1.8，dsDNA受RNA污染，小于1.8，受蛋白质污染。The ratio in pure dsDNA is 1.8, 2.0 in pure RNA, about 0.5 in protein. In dsDNA samples, RNA contaminated when its greater th

38、an 1.8, protein contaminated when its less than 1.8protein-0.5 dsDNA-1.8 pure RNA-2.0 dsDNA和RNA的热变性（thermal denaturation）；快速和慢速降温下的DNA复性（renaturation）随着温度升高，RNA的双链部分的碱基堆积会减少，光吸收值增大，短碱基对区域变性比长区域快；dsDNA分子末端以及内部富含A-T区域的变性使附近螺旋不稳定，在Tm共同变性。冷却可以使热变性DNA复性（复原），快速降温，各单链配对碱基或小部分与原链互补配对，光吸收下降小；慢速冷却，两单链互补配对，可以形

39、成完全的双链，具有与原来相同的光吸收值Section DReplicon：复制子，DNA分子中能独立进行复制的最小功能单位，包含一个复制起始点，有时候还有一个终点，any piece of DNA which replicates as a single unit, contains an origin and sometimes a terminusOrigin:复制起始点，在单个复制子内的DNA复制的固定起始位置，所有的起始点都在双链最初解链处且均富含AT序列，富含AT的起始点俾富含GC的起始点更易解链，the initiation of DNA replication within a

40、replicon always occurs at a fixed point. All orgins contain AT-rich sequences where the strands initially separate, AT-rich are more easily opened than GC-rich regions.Terminus: 终点，两个复制叉从起始点向两个方向进行复制，随着双链的解链模板被复制直至终点，two replication forks proceed bidirectionally away from the origin and the strands

41、are copied as they separate until the terminus is reached.RNA priming: RNA引导，前导链及所有的后随链片段的DNA合成是都由短的RNA片段引导起始，然后沿DNA模板延伸，有助于保持高度的复制保真性, the leading strand and all lagging strand fragments are primed by synthesis of a short piece of RNA which is then elongated with DNA, helps to maintain high replica

42、tional fidelity.Replisome (复制小体): 执行DNA复制功能的、由多种蛋白质构成的复合体DnaB: DNA解旋酶，利用ATP水解的能量结合并解开双链DNA的一种酶，the DNA helicase, the enzymes which use the energy of ATP hudrolysis to move ino and melt dsDNA.Proofreading: 校正，指蛋白质或核酸合成中的纠错机制，有助于维持复制的高度忠实性，helps to maintain high replicational fidelity.Semi-conservativ

43、e replication:半保留复制，在DNA复制中两条亲代链分开，分别作为模板指导酶催化的新生互补子链的合成，并遵循标准的碱基配对原则，亲代链分开及新生DNA开始复制处为复制叉，模板以35方向被读，新生链以53方向合成，大肠杆菌N标记培养，the two parental strands separate and each acts as a template to direct the enzyme-catalyzed synthesis of a new complementary daughter strand following the normal base-pairing ru

44、les, the point at which separation of the strands and synthesis of new DNA takes place is the replication fork, the template strands are read in the 35 direction while the new strands are synthesized 53.Semi-discontinuous replication: 半不连续复制，前导链从起始点按53方向进行连续复制，而后随链不立即复制，而是被短片段取代，后随链的复制从复制叉处开始按53的反方向

45、朝向起点形成第一个冈崎片段，随着复制叉的前进，前导链继续被复制成连续长链，而后随链片段按反方向以不连续方式被复制Okazaki fragments：冈崎片段，在DNA不连续复制过程中，沿着后随链的模板链合成的新DNA片段，真核生物的冈崎片段长度约为100200 nt，而原核生物的为10002000 ntl Prokaryotic genome is a single circular DNA and contains a single replicon. 原核基因组是一个包含单个复制子的单环DNAl Eukaryotic genome contains multiple linear chro

46、mosomes and has multiple replicons on each chromosome. 真核生物基因组包含很多线性染色体，而每个染色体中有很多复制子l All prokaryotic chromosomes and many bacteriophage and viral DNA molecules are circlular and comprise single replicons. 所有的原核生物染色体、许多噬菌体以及病毒的DNA分子都呈环形并由单一复制子构成l DNA primase lead to synthesize a short RNA primer fo

47、r synthesis of the leading strand. DNA引发酶引导一小段的RNA引物合成，引发先导链的复制l In cell cycle, which phase is for DNA replication? And describe the replication order for euchromatin, heterochromatin Centromeric DNA and telomeric DNA. 在细胞周期中，DNA的复制有哪些时期？描述常染色质、异染色质、着丝点的DNA和端粒DNA的复制顺序有4个时期：G1期、S期、G2期和M期；S期是DNA复制的时期，

48、在S期的早期主要是常染色质的复制，在S期的较晚期主要是异染色质，最后的是着丝粒DNA和端粒DNAS: DNA replicationEarly S-phase: euchromatin replicationLate S-phase: heterochromatin replicationCentromeric and telomeric DNA replicate at last l What are the similarities and differences of DNA replication in prokaryotic and eukaryotic cells? DNA复制在原

49、核生物和真核生物间的异同？Similarities:1. Semi-conservative replication 半保留复制2. Semi-discontinuous repliction 半不连续复制3. DNA helicase, Ssb DNA解旋酶是Ssb4. RNA priming RNA引物5. Proofreading 矫正Differences:1. Origin (single/multiple) 复制起点：单个/多个2. Initiation (multiple/one times) licensing factor 起始（多次/一次）许可因子3. Rate of re

50、plication fork movement (900/50 nt/S) 复制叉的移动速度（900/50 nt/s）(50,000/3,000 bp/min)4. Size of Okazaki fragments (1000-2000/100-200 nt) 冈崎片段的大小（1000-2000/100-200 nt）5. Telomeres and telomerases 端粒和端粒酶6. Polymerases (simple/complex) 聚合酶（简单/复杂）Section EMutagenesis: 诱变，用物理、化学和生物因子使基因发生突变的过程，an event capabl

51、e of causing a mutationDirect mutagenesis:直接诱变，如果一种碱基类似物或配对特性与亲本链碱基不同的修饰碱基在复制叉通过之前未被DNA修复机制去除，结果会引入一个错配碱基，而第二轮复制会将这突变永远固定下来，if a base analog or modified base whose base pairing properties are different from the parent base is not removed by a DNA repair mechanism before passage of a replication fork

52、, then an incorrect base will be incorporated, a second round of replication fixes the mutation permanently in the DNAIndirect mutagenesis:间接诱变，在复制叉通过之前，DNA中的大部分损伤都会被直接地无错恢复或切除修复机制所修复。如果未能被修复，就会发生与特定DNA聚合酶有关的一种转移损伤DNA合称的易错形式，结果是一个或多个错配碱基被掺入在损伤部分的对应位点，most lesions in DNA are repaired by error-free di

53、rect reversal or excision repair mechanisms before passage of a replication fork. If this is not possible, an error-prone form of translesion DNA synthesis may take place involving specialized DNA ploymerases and one or more incorrect bases become incorporated opposite the lesion.Mutation: 突变，DNA碱基序

54、列水平上的永久性的、可遗传的改变，产生于DNA复制或减数分裂重组过程中的自发性错误，或者是由于物理或化学试剂损伤DNA所致，最简单的突变是点突变，permanent, heritable changes in te base sequence of DNA, caused by spontaneous errors in DNA replication of meiotic recombination or the damaging effects of physical or chamical agents on the DNA. Point mutation a single base c

55、hange is the simplest mutation.Mutagen: 诱变剂，通过诱导DNA上的突变增加突变率的物质substitution mutation: 替换突变，分为转换（嘌呤-嘌呤、嘧啶-嘧啶）和颠换（嘌呤-嘧啶），transition(purine-purine, pyrimidine-pyrimidine), transversion(purine-pyrimidine)deletion mutation: 缺失突变，碱基丢失，引起基因移码突变，loss of bases and cause frameshift mutationinsertion mutation:

56、 插入突变，碱基增添，引起基因移码突变, addition of bases and cause frameshift mutationDNA damage: DNA损伤，DNA正常的化学或物理结构的改变，an alteration to the normal chemical or phusical srtucture of the DNADNA recombination：DNA重组，DNA分子内或分子间发生的遗传信息的重新共价组合过程，包括同源重组、特异位点重组和转座重组等。同源重组：在真核生物减数分裂过程中，两条DNA分子之间发生同源区域的交换，依靠recA，同源重组复制可使未修复损伤

57、的DNA恢复原来的完整性；位点特异性重组：发生在非同源DNA的特异片段之间的交换，不需recA或单链DNA；转座作用：是较短的DNA序列，可以转移进细胞基因组的几乎所有位置，因不需要序列间具有同源性也不是位点特异性的而效率低。Homologous recombination: the exchange of homologous regions between two DNA moleules occurs extensively in eukaryotes during meiosis, recA-dependent. Site-specific recombination: the exc

58、hange of nonhomologous regions of DNA at specific sites is independent of recA or ssDNA. Transposition: small DNA sequences that can move to virtually any position in a cells genome, requires no homology between sequences and is not site-specific so that relatively inefficient.l Which conditions could Damage DNA and cause mutations?什么条件下可以损伤DNA而导致突变？化学试剂或射线，化学诱变剂（碱基类似物）可以在DNA复制过程中以错配方式导