分子生物学习题答案 第一章 绪论 Chapter 1 Introduction
一 名词解释
1．人类基因组计划：与曼哈顿原子弹计划和阿波罗登月计划相媲美的美国人类基因组计划（human genome project, HGP)，解读人基因组上的所有基因、24个染色体DNA分子中的碱基序列。在―人类基因组计划‖中，分为两个阶段：DNA序列图以前的计划和DNA序列图计划。序列图前计划包括遗传图、物理图、转录图。
2. RFLP (restrict fragment length polymorphism )：A variation from one individual to the next in the number of cutting sites for a given restriction endonuclease in a given genetic locus.
3. DNA指纹：基因组中存在着多种重复序列，拷贝数从几个到数十万个，可分为串联重复序列和分散重复序列。根据个体重复序列拷贝的位置和数目的差异，使用限制性内切酶，获得具有个体特异性的DNA片段。可以作为亲缘关系或个人身份的鉴定。
4. SNP（single nucleotide polymorphism, 单核苷酸多态性）：在一个群体中，基因组内某一特定核苷酸位置上出现2种或2种以上不同核苷酸的现象，在群体中相应频率为1-2%。如果低于这个频率，可视为点突变。 二 简答
1. What is molecular biology？
Molecular biology is the subject of gene structure and function at the molecular level.
To explain the principle of development, metabolism, heredity and variation, aging at the molecular level. It grew out of the disciplines of genetics and biochemistry. 2. Major events in the genetics century
第二章 核酸、蛋白质结构
一 选择题： B, E, D, A, A 二 名词解释
1．Transfection：describes the introduction of foreign material into eukaryotic cells using a virus vector or other means of transfer. The term transfection for non-viral methods is most often used in reference to mammalian cells, while the term transformation is preferred to describe non-viral DNA transfer in bacteria and non-animal eukaryotic cells such as fungi, algae and plants.
2．Configuration：The configuration of a molecule is the permanent geometry that results from the spatial arrangement of its bonds. The ability of the same set of atoms to form two or more molecules with different configurations is stereoisomerism.
Configuration is distinct from chemical conformation, a shape attainable by bond rotations.
3．构象：(Conformation, generally means structural arrangement），指一个分子中不改变共价键结构，仅是单键周围的原子旋转所产生的原子空间排列。
4．Genetic code：The genetic code is the set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins (amino acid sequences) by living cells.
5．Codon：Specifically, the code defines a mapping between tri-nucleotide sequences called codons, and amino acids; every triplet of nucleotides in a nucleic acid sequence specifies a single amino acid.
6．Initiation codon：ATG and AUG denote sequences of DNA and RNA respectively that are the start codon or initiation codon encoding the amino acid methionine (Met) in eukaryotes and a modified Met (fMet) in prokaryotes
7．Termination codon：In the genetic code, a stop codon (or termination codon) is a nucleotide triplet within messenger RNA that signals a termination of translation. Proteins are unique sequences of amino acids, and most codons in messenger RNA correspond to the addition of an amino acid to a growing protein chain — stop codons signal the termination of this process, releasing the amino acid chain. In the standard genetic code, there are three stop codons: UAG (\(\
8．Domain：A protein domain is a part of protein sequence and structure that can evolve, function, and exist independently of the rest of the protein chain. Each domain
forms a compact three-dimensional structure and often can be independently stable and folded. Many proteins consist of several structural domains. One domain may appear in a variety of evolutionarily related proteins. Domains vary in length from between about 25 amino acids up to 500 amino acids in length. The shortest domains such as zinc fingers are stabilized by metal ions or disulfide bridges. Domains often form functional units, such as the calcium-binding EF hand domain of calmodulin. Because they are self-stable, domains can be \by genetic engineering between one protein and another to make chimera proteins.
结构域，蛋白质亚基结构中明显分开的紧密球状结构区域，又称辖区。 9．超二级结构：Super secondary structure，蛋白质分子中的二级结构聚集体。蛋白质(尤其是球状蛋白质)中若干个相邻的二级结构单元(即α-螺旋，β-折叠片和β-转角等)组合在一起，彼此相互作用，形成很有规律且空间上能辨认的结构聚集体。超二级结构在结构的组织层次上高于二级结构，充当三级结构的构件，但没有完整的结构域。根据超二级结构的组成，可分为三种类型：(1)螺旋型的聚集体(αα型)；(2)α螺旋与β折叠的聚集体(βαβ型)；(3)β折叠的聚集体(βββ型和βcα螺旋)与β折叠的聚集体(βαβ型)；(4)β折叠的聚集体(βββ型和βαβ型)。 10．核糖核酸RNA: (Ribonucleic acid), 由A，G，C，U组成。
11．脱氧核糖核酸DNA: (deoxyribonucleic acid), 由A，G，C，T组成。 12．Superhelix： is a molecular structure in which a helix is itself coiled into a helix. This is significant to both proteins and genetic material, such as overwound circular DNA.
三 简答与论述
1．What is mRNA?
mRNA is Messenger RNA (mRNA) provides an intermediate that carries the copy of a DNA sequence that represents protein
2．举例说明维持生物大分子结构的力有哪些？ 氢键，疏水力，静电作用，偶极作用 3．简述蛋白质二级结构的类型及结构
α-螺旋：是一个类似棒状的结构，紧密卷曲的多肽链构成了棒的中心部分，侧链伸出螺旋排布在外面，完成一个螺旋需要3.6个氨基酸残基，螺旋每上升一圈向上平移0.54nm，相邻两个氨基酸之间的轴心距为0.15nm，每一个氨基酸残基都沿轴旋转100o.
β-转角：也叫β-弯曲, β-回折，发夹结构，一般由四个连续的氨基酸组成。第一个氨基酸的羧基和第四个氨基酸的氨基之间形成氢键。
β-折叠 ：又称β-折叠片层结构。是肽链主链或某一肽段的一种相当伸展的结构，形成一般需要两条或两条以上的肽链共同参与，即两条或多条几乎完全伸展的多肽链侧向聚集在一起，相邻肽链主链上的氨基和羧基之间形成有规则的氢键，维持结构的稳定性。
4．为什么说蛋白质的一级结构决定其高级结构？
蛋白质的变性是可逆的，即变性的蛋白在一定的条件下之所以能自动折叠成天然的构象，是由于形成复杂的三维结构所需的全部信息都包含在它的氨基酸排列顺序上。蛋白质多肽链的氨基酸排列顺序包含了自动形成正常构象所需要的全部信息，即一级结构决定其高级结构。由于蛋白质特定的高级结构的形成，出现了它特有的生物活性，蛋白质实现其生物学功能，是决定于它的一级结构。