福建农林大学期末考试试卷2008——2009学年第学期课程名称：分子生物学考试时间120 分钟专业年级班学号姓名一、填空题（每空0.5分，共10分）1、The enzymes needed in the bacterial DNA replication are topoisomerase, helicase, _____________, DNA polymerase and ______________.（引物酶；DNA连接酶）2、There are five families of histones:________, ________, ________ and ________, known as the core histones, and H1.（H2A；H2B；H3；H4）3、The holoenzyme of E.coli RNA polymerase is_______________，the core enzyme is made up of _______________，while the___________ factor has the ability to recognize specific binding sites.（α2ββ’σ；α2ββ’；σ）4、There are two kinds of mutagens, one is physical mutagens, such as_____________，the other is chemical mutagens, such as_____________.（各种射线；碱基类似物/烷化剂/亚硝酸/EB）5、The two-dimensional structure of tRNA is . And the three-dimensional structure of tRNA is . （三叶草型、L型）6、was suggseted by Crick to explain the redundancy of the genetic code.（摆动假说）7、The start codon is . There are three stop codons: , , .（A TG或AUG、TAA或UAA、TAG或UAG、TGA或UGA）8、site is where incoming aminoacyl-tRNA molecules bind, and site is where the growing polypeptide chain is usually found.（A、P）二、名词解释（每小题2分，共30分）1、semi-conservative replication：半保留复制，亲代双链DNA以每条链为模板，按碱基配对原则各合成一条互补链，这样一条亲代DNA双螺旋，形成两条完全相同的子代DNA 螺旋，子代DNA分子中都有一条合成的“新”链和一条来自亲代的旧链。

2、Tm：核酸热变性温度范围的中点。

3、asymmetry of transcription：转录的不对称性，指双螺旋的DNA进行转录时只有一条链能被转录，另一条链可能起调节作用。

4、transition：在基因突变中，一个嘌呤被另一个嘌呤所代替或一个嘧啶被一个另嘧啶所代替的现象。

5、exon：外显子，指真核生物基因中，含有蛋白质编码信息区段、在成熟mRNA的加工过程中被保留下来的部分。

6、transposon：转座子，基因组上一些可由一个位置移动到另一位置的核酸序列。

7、operon：原核基因表达调控的单位，包括启动子、操纵基因和一系列功能相关的结构基因。

8、Synonymous codon：编码同一氨基酸的密码子。

9、Ribosome：核糖体，蛋白质合成的场所。

10、Shine-Dalgarno sequence ：SD序列，由Shine和Dalgarno发现原核生物起始密码子上游8~13个nt的保守多嘌呤序列，与核糖体16S小亚基的特定序列碱基配对，相对于起始密码子正确定位核糖体，保证翻译的准确。

11、housekeeping gene：生物体不同发育时期所有类型细胞中均保持表达状态的基因。

12、Ribozyme：核酶，能够催化特定生化反应的RNA分子。

13、Chaperone：分子伴侣，帮助蛋白质分子形成正确空间构象的辅助分子。

14、DNA clone：DNA克隆，将片段相对较短的目的核酸片段与能进行独立复制的载体连接形成重组DNA，重组DNA能够在寄主细胞内增殖，从而获得大量的目的核酸片段。

15、phage：侵染细菌的病毒。

三、单项选择题（每小题1分，共15分）（D）1、DNA replication in eukaryotes:A. usually starts at the same place every timeB. only involve 2 different DNA polymerasesC. is faster than in bacterial DNA replicationD. all of the above are false（D）2、Which of the following are true statements regarding telomeres:A. they stabilize linear chromosomesB. they consist of a short repeating sequenceC. they are located at the chromosome endsD. all of the above are true（C）3、Mismatches produced from replication errors are first recognized by ________ for the purposes of repair.A. MutHB. MutM and MutLC. MutL and MutSD. Exonuclease I（B）4、Transcription in prokaryotes and the eukaryotic nucleus:A. is catalyzed by the same enzymeB. involves Watson-Crick type pairing of nucleotidesC. requires a primerD. proceeds from 3’ to5’（C）5、Which of the following is an example of highly-repetive DNA?A. Alu elementB. Histone gene clusterC. Minisatellite DNAD. KpnI family（C）6、Which of the following is not involved in homologous recombination in E. coli that we studied in class:A. RecAB. RecBCDC. RecQD. RuvA （B）7、Regulation of the Lac operon is belong to:A. repression of negative controlB. induction of negative controlC. repression of positive controlD. induction of positive control （D）8、which of the following descriptions of subunits of DNA polymerase III holoenzyme is true？A. the βsubunits clamp the polymerase to the DNAB. the τsubunits link the two catalytic cores togetherC. the αsubunits contribute the DNA polymerase activityD. all of the above are ture（B）9、Nuclear mRNA splicing is performedA. in nucleosomesB. in spliceosomesC. in the nucleolus C. in ribosome（ C ）10、Cap functions not includeA. enhancing splicing of the first intronB. enhancing translation of the mRNAC. enhancing degradation of the mRNA in the cytoplasmD. enhancing the stablitity of the mRNA（D）11、Which of the following is true of the genetic codeA. it is read 3 nucleotides at a timeB. it is not overlappingD. it is degenerate (more than one triplet codes for most amino acids)D. a and b are true（A）12、The region(s) of tRNA recognized by amino-acyl tRNA synthetases (so that they can charge the right tRNA) isA. the CCAB. the D loopC. the anticodon C. the T or pseudouridine loop （C）13、In nuclear mRNA splicing, the intron is released as aA. circular RNAB. linear RNAC. lariat RNAD. a “Y” RNA（ B ）14、The first and main polyadenylation signal is foundA. 20-30 bp from the ORFB. 20-30 bp from the polyadenylation siteC. 20-30 bp from the promoter siteD. 20-30 bp from the end of the RNA（A）15、During initiation step of the translation in prokaryotes, the components involved areA. ribosome, mRNA, initiator tRNA charged, initiator factors, GTPB. ribosome, mRNA, initiator tRNA charged, initiator factors, ATPC. ribosome, mRNA, initiator tRNA charged, initiator factors, CTPD. ribosome, mRNA, initiator tRNA charged, initiator factors, TTP四、问答题（45分）1、Please illuminate the main content of central dogma and draw the sketch map.（10 points）DNA是生物遗传的主要物质基础。