生化作业答案.docx

1、生化作业答案一、用汉语和英语解析以下名词（Terminology）1.Differential centrifugation：Because of differences in the two substances the separation. 差异离心：由于两种物质的差异而进行的分离。2.Isopycnic centrifugation ：Chemists and biologists may increase the effective gravitational force on a test tube so as to more rapidly and completely caus

2、e the precipitate (“pellet”) to gather on the bottom of the tube. The remaining solution is properly called the “supernate” or “supernatant liquid” 密度梯度离心 ：如果蛋白质颗粒在具有密度梯度的介质中离心时，质量和密度大的颗粒比质量和密度小的沉降得快，并且会沉降到与自身密度相等的梯度时，即停滞不前，最后各种蛋白质在离心管中被分离成各自独立的区带，达到离心效果。 3.Sedimentation coefficient ：The sedimentati

3、on coefficient S of a particle is used to characterize its behavior in sedimentation processes. 沉降系数：表征微粒在沉降过程中微粒的运转情况的特征参数。4.Metabolome：amino acids, nucleotides, sugars and their phosphorylated derivatives, and a number of mono-, di-, and tricarboxylic acids. Secondary metabolites.代谢物组：包括氨基酸，核苷酸，糖类

4、及其衍生物和大量的含有单双三羧基酸次生代谢产物 5.Configuration：refers to the order that is determined by chemical bonds. The configuration cannot be altered unless chemical bonds are broken and reformed. 构型：指的是由化学键作用决定的顺序，构型不会轻易改变除非化学键断裂或变形 6.Conformation：refers to order that arises from the rotation of molecules about th

5、e single bonds. 构象：由于单键分子键旋转而产生的7.Dynamic steady state：refer to constancy of concentration. Maintaining this steady state requires the constant investment of energy; 8.Endosymbiosis：Eukaryotic cells acquired the capacity for photosynthesis and for oxidative phosphorylation from endosymbiotic bacteri

6、a. 内共生：j将可以进行光合作用和氧化磷酸化作用的细菌内吞并为真核细胞提供能量的一种现象。9.Hydrogen bonds : Electronegativity of hydrogen atoms to form groups with great dipole moment, electron to the atom electronegativity of the great migration to the bare proton, really experience another negative charge of hydrogen atoms generated strong

7、 electrostatic attraction, the hydrogen bond.氢键：电负性原子与氢形成基团具有很大的偶极矩，电子云向电负性大的原子偏移使氢质子裸露，当正电荷氢遇到另一负电性强的原子时产生静电吸引，即氢键。10.Ionic interactions: Different parts of the same molecule or different molecules on the positive and negative electric Heji chemical bond formed between the groups离子键：同一分子的不同部位或不同分子上

8、的正负电荷基团之间所形成的化学键。 11.Hydrophobic (Greek,“water-fearing”) interactions：Water molecules in the exclusion of non-polar, non-polar groups or molecules in aqueous solution appears the trend of mutual association. 疏水性：于水对非极性分子的排斥，非极性基团或分子在水溶液中出现相互缔合的趋势。12.Van der Waals interactions：Intermolecular forces i

9、s also known as van der Waals force, its essence, is an electrical attraction, so study the origin of intermolecular forces have to study the electrical properties of molecular materials and molecular structure.范德华力：分子间作用力又被称为范德华力，按其实质来说是一种电性的吸引力，因此考察分子间作用力的起源就得研究物质分子的电性及分子结构。14.Osmosis：When using s

10、emi-permeable membrane to separate two different concentrations of the solution, the lower the concentration of the solution in the solvent (water) flows automatically through the semi permeable membrane solution of higher concentration until the chemical potential until equilibrium phenomenon.渗透：当利

11、用半透膜把两种不同浓度的溶液隔开时，浓度较低的溶液中的溶剂(如水)自动地透过半透膜流向浓度较高的溶液，直到化学位平衡为止的现象。二、 问答（首先翻译以下问题，然后以汉语或英语回答）1药物作用和分子构型 几年前，两家公司都推出了名为苯丙胺和中枢神经刺激剂的药物，药物结构如下： 经鉴定它们的物理性质（C H N结构分析.熔点.溶解度）都是相同的。但是中枢神经刺激剂（至今仍被使用）的建议用量是5毫克/天。苯丙胺（已不再被使用）是前者的两倍。显与神经中枢刺激剂相比这需要更多的苯丙胺，解释一下这个明显的原因。答：与氨基相连的碳为手性碳，具有手性的同分异构体，苯丙胺应是由药物与药物的手性异构体共同组成，而

12、中枢神经刺激剂仅含药物一种成分，所以所需剂量为前者的一半，前者必会在竞争中被淘汰。2.官能团的鉴别 下面的图片是常见的生物大分子的官能团，由于生物大分子的大部分性质都是由官能团决定的，所以能够识别一些官能团很重要，在下面的大分子中圈出官能团并且命名。三、从生物化学角度解释以下现象1. 水滴落到某些植物叶片表面会迅速滑落（左图），而落入纸张会被吸收（右图）， 从叶片表面和纸张的成分解释此现象。 纸张由植物纤维、填料、胶料、色料等组成，由于相似相容水会被吸收。叶片表面由一些角质大分子构成，趋于极性，与水不容所以滚下。2. 含羞草为豆科多年生草本或亚灌木，学名Mimosa pudica，它在受到外界

13、触动时，叶柄下垂，小叶片合闭，此动作被人们理解为“害羞”，从渗透的角度解释此现象。它的羽状复叶的叶柄和小叶的基部都有一个膨大的叶枕，叶柄中心有个大维管束，周围有许多薄壁细胞，这些薄壁细胞间有比较大的细胞间隙。薄壁细胞含有很多水分，保持着膨压，使叶柄挺起和小叶张开。可是，当它受到机械刺激或人的手触动时，产生的动作电位传递到小叶基部，就使叶枕上半部的薄壁细胞的水分马上渗透进细胞隙，使细胞的膨压骤然下降，但下半部的薄壁细胞仍维持原来的膨压，如此上半部与下半部膨压的不平衡，就使小叶片一个个直立起来，此时我们就看到含羞草的叶于闭合。如果机械震动的刺激大，电信号还能传导到叶柄基部的叶枕，使其下半部的细胞膨

14、压降低，于是叶柄连同小叶就一齐垂下。一、用汉语和英语解析以下名词（Terminology）1. amino acids（氨基酸）：同时含有一个或多个氨基和羧基的脂肪族有机酸。根据氨基和羧基的位置，有氨基酸和氨基酸等类型。参与蛋白质合成的常见的是20种L-氨基酸。English：Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an a

15、mino acid are carbon, hydrogen, oxygen, and nitrogen.2. isoelectric point (等电点)：蛋白质或两性电解质(如氨基酸)所带净电荷为零时溶液的pH，此时蛋白质或两性电解质在电场中的迁移率为零。English：isoelectric point (pI), sometimes abbreviated to IEP, is the pH at which a particular molecule or surface carries no net electrical charge.3. peptide（肽）：两个或两个以上氨

16、基酸通过肽键共价连接形成的聚合物。English：Peptides are short polymers of amino acid monomers linked by peptide bonds. 4. protein（蛋白质）：生物体中广泛存在的一类生物大分子，由核酸编码的氨基酸之间通过氨基和羧基形成的肽键连接而成的肽链，经翻译后加工而生成的具有特定立体结构的、有活性的大分子。English：Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a g

17、lobular or fibrous form, facilitating a biological function.5. peptide bond（肽键）：一个氨基酸的羧基与另一氨基酸的氨基发生缩合反应脱水成肽时，羧基和氨基形成的酰胺键。具有类似双键的特性.English：A peptide bond (amide bond) is a covalent chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the o

18、ther molecule, causing the release of a molecule of water (H2O), hence the process is a dehydration synthesis reaction (also known as a condensation reaction), and usually occurs between amino acids.6. conjugated protein（结合蛋白）：结合蛋白质是单纯蛋白质和其他化合物结合构成，被结合的其他化合物通常称为结合蛋白质的非蛋白部分(辅基)。English：A conjugated p

19、rotein is a protein that functions in interaction with other chemical groups attached by covalent bonds or by weak interactions.7. prosthetic group（辅基）：辅基是与酶、蛋白共价结合的金属离子或一类有机化合物。English：A cofactor is a non-protein chemical compound that is bound to a protein and is required for the proteins biologic

20、al activity. These proteins are commonly enzymes, and cofactors can be considered helper molecules that assist in biochemical transformations.8.dialysis（透析）：透析是通过小分子经过半透膜扩散到水（或缓冲液）的原理，将小分子与生物大分子分开的一种分离纯化技术。 English：dialysis is a process for removing waste and excess water from the blood, and is prim

21、arily used to provide an artificial replacement for lost kidney function in people with renal failure.9.ion-exchange chromatography（离子交换色谱法）： English：Ion-exchange chromatography (or ion chromatography) is a process that allows the separation of ions and polar molecules based on their charge.10. gel

22、filtration chromatography（凝胶色谱）： English：Use have certain size of gel chromatography for pore medium (such as polydextran gel, agarose gel, polyacrylamide gel, etc), use gel particle on molecular weight and shape of the differing physical separation of chromatography technology. Because all sorts of

23、 molecular size, shapes, and of different spread to gel within different pore speed, and through the layers of the different speed column chromatography separation.11. affinity chromatography（亲和层析）：利用共价连接有特异配体的层析介质分离蛋白质混合物中能特异结合配体的目的蛋白或其他分子的一种层析法。English：Affinity chromatography is a method of separa

24、ting biochemical mixtures and based on a highly specific interaction such as that between antigen and antibody, enzyme and substrate, or receptor and ligand.12.SDS-gel electrophoresis（SDS-gel电泳）： English：In the polyacrylamide gel to join in the SDS, eliminate the protein molecules net charge differe

25、nces, and make protein molecules diameter similar prevalent form, in the gel electrophoresis, the relative molecular mass of the smaller protein molecules move the faster the speed, in this way the protein in the samples can be separated by molecular size components, but also can be used to determin

26、e the relative molecular mass protein.13. isoelectric focusing（等电聚焦）：使电泳的介质中形成一定范围的pH梯度，电泳时待分离的两性分子可以在这种pH梯度中迁移，直到聚集于与其等电点相同的区域。该技术特别适用于分子量相近而等电点不同的蛋白质分离和分析。English：Isoelectric focusing (IEF), also known as electrofocusing, is a technique for separating different molecules by their electric charge d

27、ifferences. It is a type of zone electrophoresis, usually performed on proteins in a gel, that takes advantage of the fact that overall charge on the molecule of interest is a function of the pH of its surroundings.14. primary structure（一级结构）：由多个单体以共价键组成的生物大分子中不同单体的排列顺序。包括结构单元(单体、亚基)的化学结构、立体化学构型和构象，

28、结构单元之间的键连接和序列等。就蛋白质的一级结构而言，是指氨基酸的序列，此外还包括共价连接的非肽组成，即指蛋白质中所有组成的共价连接方式。English：The Primary structure of a biological molecule is the exact specification of its atomic composition and the chemical bonds connecting those atoms (including stereochemistry). For a typical unbranched, un-crosslinked biopoly

29、mer (such as a molecule of DNA, RNA or typical intracellular protein), the primary structure is equivalent to specifying the sequence of its monomeric subunits.15. secondary structure（二级结构）：多肽链或多核苷酸链沿分子的一条轴所形成的旋转和折叠等，主要是由分子内的氢键维系的局部空间排列。如蛋白质的螺旋、片层、转角、无规卷曲及DNA的双螺旋结构。English：Biomolecular structure is

30、the structure of biomolecules, mainly proteins and the nucleic acids DNA and RNA. The structure of these molecules is frequently decomposed into primary structure, secondary structure, tertiary structure, and quaternary structure.16. tertiary structure（三级结构）：生物大分子在二级、超二级结构的基础上进一步盘绕形成的高级结构。如多肽链和多核苷酸链

31、所形成的不规则三维折叠。三级结构产生于肽链上氨基酸侧链之间或多核苷酸链上碱基与碱基(或核糖)之间的相互作用。English：the tertiary structure of a protein or any other macromolecule is its three-dimensional structure, as defined by the atomic coordinates. Proteins and nucleic acids are capable of diverse functions ranging from molecular recognition to cat

32、alysis.17. quaternary structure（四级结构）：蛋白质的层次结构中的第四个层次，特指组成蛋白质的各个亚基通过非共价键相互作用(包括疏水相互作用、氢键和盐键等)排列组装而成的立体结构。English：In biochemistry, quaternary structure is the arrangement of multiple folded protein or coiling protein molecules in a multi-subunit complex. For nucleic acids, the term is less common, but can refer to the higher-level organization of DNA in chromatin, including its interactions with histones, or to the interactions between separate RNA units in the ribosome or spliceosome.18. Homo