分子生物学-特纳第二版课后练习题

1、Section C - properties of nucleic acids1The sequence 5'-AGTCTGACT-3' in DNA is equivalent to which sequence in RNA? A 5'-AGUCUGUGACU -3' B 5' -UGTCTGUTC -3' C 5' -UCAGUCUGA-3' D 5'- AGUCAGACU-3' 2. Which of the following correctly describes A-DNA? A a right-ha

2、nded antiparallel double helix with 10 bp/turn and bases lying perpendicular to the helix axis. B a left-handed antiparallel double-helix with 12 bp/turn formed from alternating pyrimidine-purine sequences. C a right-handed antiparallel double helix with 11 bp/turn and bases tilted with respect to t

3、he helix axis. D a globular structure formed by short intramolecular helices formed in a single-strand nucleic acid. 3. Denaturation of double stranded DNA involves.A breakage into short double-stranded fragments.B separation into single strands. C hydrolysis of the DNA backbone.D cleavage of the ba

4、ses from the sugar-phosphate backbone. 4. Which has the highest absorption per unit mass at a wavelength of 260 nm?A double-stranded DNA. B mononucleotides. C RNA. D protein. 5. Type I DNA topoisomeraes .A change linking number by士2 B require ATP. C break one strand of a DNA double helix. D are the

5、target of antibacterial drugs. Section D - Prokaryotic and eukaryotic chromatin structure1Which of the following is common to both E. coli and eukaryotic chromosomes? A the DNA is circular. B the DNA is packaged into nucleosomes.C the DNA is contained in the nucleus. D the DNA is negatively supercoi

6、led. 2A complex of 166 bp of DNA with the histone octamer plus histone HI is known as a . . . A nucleosome core. B solenoid. C 30 nm fiber. D chromatosome. 3In what region of the interphase chromosome does transcription take place? A the telomere. B the centromere. C euchromatin. D heterochromatin.

7、4 Which statement about CpG islands and methylation is not true? A CpG islands are particularly resistant to DNase I. B CpG methylation is responsible for the mutation of CpG to TpG in eukaryotes. C CpG islands occur around the promoters of active genes. D CpG methylation is associated with inactive

8、 chromatin. 5Which of the following is an example of highly-repetitive DNA? A Alu element. B histone gene cluster. C DNA minisatellites. D dispersed repetitive DNA. Section E - DNA replication1The number of replicons in a typical mammalian cell is . . . A 40-200. B 400. C 1000-2000. D 50000-100000.

9、2. In prokaryotes,the lagging strand primers are removed by . . . A 3' to 5' exonuclease. B DNA ligase. C DNA polymerase I. D DNA polymerase III. 3. The essential initiator protein at the E. coli origin of replication is . . . A DnaA. B DnaB. C DnaC. D DnaE. 4. Prokaryotic plasmids can repli

10、cate in yeast cells if they contain a cloned yeast. . . A ORC. B CDK. C ARS. D RNA. Section F - DNA damage, repair and recombination(此章不考)1. Per nucleotide incorporated, the spontaneous mutation frequency in E. coli is . . . A 1 in 106. B 1 in 108. C 1 in 109. D 1 in 1010. 2. The action of hydroxyl

11、radicals on DNA generates a significant amount of . . . A pyrimidine dimmers.B 8-oxoguanine.C O6- methylguanine. D 7-hydroxymethylguanine.3. In methyl-directed mismatch repair in E. coli, the daughter strand containing the mismatched base is nicked by . . . A MutH endonuclease.B UvrABC endonuclease.

12、C AP endonuclease.D 3' to 5' exonuclease.4. The excision repair of UV-induced DNA damage is defective in individuals suffering from . A hereditary nonpolyposis colon cancer. B Crohn's disease. C classical xeroderma pigmentosum. D xeroderma pigmentosum variant. Section K - Transcription i

13、n prokaryotes 1. Which two of the following statements about transcription are correct? A RNA synthesis occurs in the 3' to 5' direction. B the RNA polymerase enzyme moves along the sense strand of the DNA in a 5' to 3' direction. C the RNA polymerase enzyme moves along the template

14、strand of the DNA in a 5' to 3' direction. D the transcribed RNA is complementary to the template strand. E the RNA polymerase adds ribonucleotides to the 5' end of the growing RNA chain. F the RNA polymerase adds deoxyribonucleotides to the 3' end of the growing RNA chain. 2. Which

15、one of the following statements about E. coli RNA polymerase is false? A the holoenzyme includes the sigma factor. B the core enzyme includes the sigma factor.C it requires Mg2+ for its activity. D it requires Zn2+ for its activity. 3. Which one of the following statements is incorrect? A there are

16、two subunits in the E. coli RNA polymerase. B there is one subunit in the E. coli RNA polymerase. C E. coli has one sigma factor. D the subunit of E. coli RNA polymerase is inhibited by rifampicin. E the streptolydigins inhibit transcription elongation. F heparin is a polyanion, which binds to the s

17、ubunit. 4. Which one of the following statements about transcription in E. coli is true? A the -10 sequence is always exactly 10 bp upstream from the transcription start site.B the initiating nucleotide is always a G. C the intervening sequence between the -35 and -10 sequences is conserved. D the s

18、equence of the DNA after the site of transcription initiation is not important for transcription efficiency. E the distance between the -35 and -10 sequences is critical for transcription efficiency. 5. Which one of the following statements about transcription in E. coli is true? A loose binding of

19、the RNA polymerase core enzyme to DNA is non-specific and unstable. B sigma factor dramatically increases the relative affinity of the enzyme for correct promoter sites.C almost all RNA start sites consist of a purine residue, with A being more common than G. D all promoters are inhibited by negativ

20、e supercoiling. E terminators are often A-U hairpin structures. Section L - Regulation of transcription in prokaryotes 1. Which two of the following statements are correct? A the double stranded DNA sequence that has the upper strand sequence 5'-GGATCGATCC-3' is a palindrome. B the double st

21、randed DNA sequence that has the upper strand sequence 5'-GGATCCTAGG-3' is apalindrome. C the Lac repressor inhibits binding of the polymerase to the lac promoter. D the lac operon is directly induced by lactose. E binding of Lac repressor to allolactose reduces its affinity for the lac oper

22、ator.F IPTG is a natural inducer of the lac promoter. 2. Which one of the following statements about catabolite-regulated operons is false?A cAMP receptor protein (CRP) and catabolite activator protein (CAP) are different names for the same protein. B when glucose is present in the cell cAMP levels

23、fall. C CRP binds to cAMP and as a result activates transcription.D CRP binds to DNA in the absence of cAMP. E CRP can bend DNA, resulting in activation of transcription. 3. Which one of the following statements about the trp operon is true? A the RNA product of the trp operon is very stable. B the

24、Trp repressor is a product of the trp operon. C the Trp repressor， like the Lac repressor, is a tetramer of identical subunits. D the Trp repressor binds to tryptophan. E tryptophan activates expression from the trp operon. F the trp operon is only regulated by the Trp represso4. Which two of the fo

25、llowing statements about attenuation at the trp operon are true? A attenuation is rho-dependent. B deletion of the attenuator sequence results in an increase in both basal and activated levels of tran- scription from th trp promoter. C the attenuator lies upstream of the trp operator sequence. D att

26、enuation does not require tight coupling between transcription and translation. E pausing of a ribosome at two tryptophan codons in the leader peptide when tryptophan is in short supply causes attenuation. F a hairpin structure called the pnti-terminator stops formation of the terminator hairpin, re

27、sulting in transcriptional read-through into the trpE gene, when tryptophan is scarce.Section M - Transcription in eukaryotes 1. Which one of the following statements about eukaryotic RNA polymerases I, II and III is false? A RNA Pol II is very sensitive to -amanitin. B RNA Pol II is located in th n

28、ucleoplasm. C RNA Pol III transcribes th genes for tRNA. D eukaryotic cells contain other RNA polymerases in addition to RNA Pol I, RNA Pol II and RNA Pol III. E each RNA polymerase contains subunits with homology to subunits of the E. coli RNA polymerase as well as additional subunits， which are un

29、ique to each polymerase. F the carboxyl end of RNA Pol II contains a short sequence of only seven amino acids which is called the carboxyl-terminal domain (CTD) and which may be phosphorylated. 2. Which two of the following statements about RNA Pol I genes are true?A RNA Pol I transcribes the genes

30、for ribosomal RNAs. B human cells contain 40 clusters of five copies of the rRNA gene. C the 185, 5.85 and 285 rRNAs are synthesized as separate transcripts. D RNA Pol I transcription occurs in the nucleoplasm. E RNA Pol I transcription occurs in the cytoplasm. F rRNA gene clusters are known as nucl

31、eolar organizer regions. 3. Which one of the following statements about RNA Pol I transcription is false? A in RNA Pol I promoters the core element is 1000 bases downstream from the upstream control element (UCE). B upstream binding factor (UBF) binds to both the UCE and the upstream part of the cor

32、e element of the RNA Pol I promoter. C selectivity factor SLl stabilizes the UBF-DNA complex. D SL1 contains several subunits including the TATA-binding protein TBP. E in Acanthamoeba there is a single control element in rRNA gene promoters. 4. Which two of the following statements about RNA Pol III

33、 genes are true? A the transcriptional control regions of tRNA genes lie upstream of the start of transcription. B highly conserved sequences in tRNA gene coding regions are also promoter sequences. C TFIIIC contains TBP as one of its subunits. D TFIIIB is a sequence specific transcription factor on

34、 its own. E in humans 5S rRNA genes are arranged in a single cluster of 2000 copies. Section 0 - RNA processing and RNPs 1. Which ribonucleases are involved in producing mature tRNA in E. coli?A RNases A, D, E and F. B RNases D, E, F and H. C RNases D, E, F and P. D RNases A, D, H and P. 2. Most euk

35、aryotic pre-mRNAs are matured by which of the following modifications to their ends? A capping at the 3-end cleavage and polyadenylation at the 5'-end. B addition of a GMP to the 5'-end，cleavage and polyadenylation to create the 3'-end. C addition of a guanine residue to the 5'-end c

36、leavage and polyadenylation to create the 3'-end. D addition of a GMP to the 5'-end，polyadenylation，then cleavage to create the 3'-end.3. Which one of the following statements correctly describes the splicing process undergone by most eukaryotic pre-mRNAs? A in a two-step reaction, the s

37、pliceosome removes the exon as a lariat and joins the two introns together. B splicing requires conserved sequences which are the 5splice site，the 3' -splice site the branch-point and the polypurine tract. C the U1 snRNP initially binds to the 5'-splice site，U2 to the branchpoint sequence an

38、d then the tri-snRNP, U4, US and U6 can bind. D in the first step of splicing the G at the 3'-end of the intron is joined to the 2-hydroxyl group of the A residue of the branchpoint sequence to create a lariat. Section P - The genetic code and tRNA 1. Which of the following list of features corr

39、ectly apply to the genetic code?A triplet degenerate nearly universal, comma-less, nonoverlapping. B triplet universal, comma-less, degenerate, nonoverlapping. C overlapping, triplet, comma-less, degenerate nearly universal. D overlapping, comma-less nondegenerate nearly universal triplet. 2. Which

40、of the following statements about tRNAs is false? A most tRNAs are about 76 residues long and have CCA as residues 74, 75 and 76. B many tRNAs contain the modified nucleosides pseudouridine dihydrouridine ribothymidine and mosme. C tRNAs have a common L-shaped tertiary structure with three nucleotid

41、es at one end able to base pair with an anticodon on a messenger RNA molecule. D tRNAs have a common cloverleaf secondary structure containing three single stranded loops called the D-, T- and anticodon loops. 3 Which three statements are true? The aminoacyl tRNA synthetase reaction. A joins AMP to

42、the 3-end of the tRNA.B is a two step reaction. C joins any amino acid to the 2'- or 3' -hydroxyl of the ribose of residue A76. D is highly specific because the synthetases use identity elements in the tRNAs to distinguish between them. E joins AMP to the amino acid to produce an intermediat

43、e. F releases PPi in the second step. Section Q - Protein synthesis 1. Which statement about the codon-anticodon interaction is false?A it is antiparallel and can include nonstandard base pairs. B inosine in the 5' -anticodon position can pair with A, C or U in the 3'-codon position C inosine in the 3-anticodon position can pair with A, C or U in the 5-codon position.D A is never found in the 5'-anticodon position as it is modified by anticodon deaminase.2 Which one of the following statements correctly describes initiation of protein synthesis in E. coli?A