分子生物学期末考试复习内容-2011

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 cells 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 ofpost-translational modification 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 histones Biomembranes: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 chainson 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 bondedhydrogen atom on a donnor group and a pair of nonbonding electronson 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 neutralmonleculesHydrophobic 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 sabilizingforce in 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 fattyacids 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 phospholipidmolecule consists of a hydrophilic polar head group and a hydrophobictail，When placed in water, the hydrophilic heads tend to face water and thehydrophobic 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质-蛋白质复合物，is a biochemical assembly that contains both proteins and lipidswater-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 forsignaling molecules such as hormons and neurotransmitters; enzymes fordegrading extracellular molecules before uptake of the products; pores orchannels 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α-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 chiralα-carbon atom linked to a proton, amino and carboxyl groups, and aspecific side chain which confers diifferent physical and chemicalproperties, behave as zwitterions in solution.Acidic\basic\polar\nonpolar\aromatic 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, 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 terminusα-helix: α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α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 secondarystructure in proteins, often found in globular proteins and in some fibrousproteins, the right-handed α-helix has 3.6 amino acids per turn and isstbbilized by hydrogen bonds between peptid N-H and C=O groups threeresidues apartβ-sheet:β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，thesecondary structure in proteins, strong and rigid, important in structuralproteins, formed by hydrogen bonding of the peptide bond N-H and C=Ogroups to the complementary groups of another section of the polypeptide chainParallel β-sheet: 正向平行的β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 β-sheet: 反向平行的β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 N→C and C→Nprimary 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α螺旋和β折叠片断，polypeptide chains are able to fold into a number of regular structures which are 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 structure Quaternary 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 proteins 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 called exons in eukaryotes Motif：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 arrived 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 geneduplication and subsequent divergent evolution of the new genes, familymembers in different species theat have retained the same function andcarry out the same biochemical role are orthologs while those that haveevolved different, but often related functions are paralogs, the degree ofsimilarity between the amino acid sequences of orthologous members of aprotein family in different organisms depengds on how long ago the twoorganisms diverged from their common ancestor and on how importantconservation 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 reactions by severalorders 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 ligandsfrom the extracellular medium and, by virtue of the resultingconformational change, initiate reactions within the cell in response to thatligand; 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 andstorage, molecules and ions are transported and stored in a protein-biundform, 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(Gelfiltration chromatography), charge( ion-exchange chromatoraphy,isoelectric focusing, electophoresis ), hydrophobicity (hydrophobicinteraction chromatography), affinity(affinitychromatography),recombinant techniques(overexpression of the proteingreatly)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α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。