分子生物学(双语)2012 A

安徽大学2012 —20 13 学年第 1 学期

《分子生物学（双语）》考试试卷（A 卷）

（闭卷 时间120分钟）

考场登记表序号

一、名

词解释题（每小题3分，共36分）

1. semiconservative replication

2. Base Excision Repair

3. rho dependent terminator

4. polycistronic mRNA

5. DNase Ⅰhypersensitivity

6. C value paradox

7. IS element

8. primase

9. elongation factor

10. topoisomerase

11. RNA interference

12. enhancer

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二、填空题（每空1.5分，共21分）

1. During DNA replication, unwinds double-stranded DNA, and removes RNA primers in the Okazaki fragments with its 5' to 3' exonuclease activity.

2. A typical prokaryotic promoter has two consensus sequences, which are termed ________ and _______. The ideal spacing between the two consensus sequences is________ .

3. Transposition occurs via two types of mechanisms. One is called ; the other is called .

4. In negative control ,the regulator protein acts as a to block transcription of the operon.

5. In SOS repair system, the two key regulatory proteins are and Lex A. Lex A is a (positive/ negative) regulator .

6. , which locates upstream of the start codon of the mRNA, binds 3' end of the 16S rRNA in the ribosome to initiate protein synthesis

7. In eukaryotes the tRNA genes are transcribed by RNA polymerase .

8. When a double-strand DNA is denatured, the absorbance at A260 will (decrease/increase). 9. The generation of antibody diversity is mainly due to .

三、单项选择题（每小题1.5分，共21分.请填入下表相应题号栏中）

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1. DNA polymerase can add nucleotides to

A. a free 3′end of a growing DNA chain

B. a free 5′end of a growing DNA chain

C. either a 3′or 5′end of a DN A chain

D. a 5′end of RNA primer

E. all of the above

2. What is the first protein to bind to a eukaryotic promoter, and at which site does it bind? A. TFIID binds to a TATA box. B. RNA polymerase II binds to a TATA box. C. A regulator protein binds to a regulator region. D. An activator protein binds to an enhancer.

3. Splicing is the process that does which of the following?

A. Add multiple adenosine bases to the end of a primary RNA transcript

B. Remove exons and join introns

C. Remove introns and join exons

D. Remove mutated regions of primary transcript RNA

4. Which subunit of the E. coli RNA polymerase holoenzyme catalyzes the synthesis of RNA ?

A. α-subunit

B. β-subunit

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C. rho factor

D. sigma factor

5. The DNA in transcriptionally active chromatin tends to be

A. highly methylated

B. fully-methylated

C. Under-methylated or non--methylated

D. Semi-methylated

6. The most efficient control of eukaryotic gene expression is achieved at the level of

A. Replication.

B. translation initiation

C. post-transcription

D. post-translation.

E. .transcription initiation.

7. Translation is terminated when a stop codon is presented at the ________.

A. E site

B. A site

C. P site

D. either A or B

E. either A or C

8. In ara operon, C protein can serve as

A. an activator

B. a repressor

C. either a repressor or an activator depending on presence/absence of arabinose

D. both a repressor and an activator irrespective of presence/absence of arabinose

9. In a standard recombinant DNA procedure, the step which follows the construction of recombinant

DNA molecule should be

A re-ligation of the vectors

B. ligating the vector with the gene of interest

C. digesting the vector with a restriction endonuclease

D. transformation of the molecule into host cells

10. Which of the following is NOT a step in a PCR reaction:

A. Annealing

B. Extension

C. Denaturation

D. dehydration

11. One important difference between DNA replication in prokaryotes and eukaryotes is that

A. prokaryotes do not use enzymes in the replication process

B. there is only one replication origin in prokaryotes

C. there are no Okazaki fragments in prokaryotes

D. replication is conservative, not semiconservative, in prokaryotes

12. A frameshift mutation could result from

A. a base insertion only.

B. a base deletion only.

C. a base substitution only.

D. either an insertion or a deletion of a base.

E. deletion of three consecutive bases.

13. Which of the enzymes below is involved in repair of both thymine dimer and deaminate cytosine in E.coli

A. DNA polymerase I

B. Photolyase

C. Uracil N-glycosylase

D. AP endonuclease

14.An IRE (iron response element) regulates the expression of iron metabolism related genes by

A. by binding to IRE-BP

B. by forming a hair-pin structure

C. at post-transcriptional or translational level

D. all of the above

四、简答题（第1小题12分，第2小题10分，共22分）

1. Describe how tryptophan concentration regulates the expression of the structural genes in the trp operon.

2. How are eukaryotic RNA precursors processed ?