分子生物学-特纳第二版课后练习题(最新整理)

1、section c - properties of nucleic acids1. the sequence 5-agtctgact-3 in dna is equivalent to which sequence in rna?a 5-agucugugacu -3b 5 -ugtctgutc -3c 5 -ucagucuga-3d 5- agucagacu-32. which of the following correctly describes a-dna?a a right-handed antiparallel double helix with 10 bp/turn and bas

2、es lying perpendicular tothehelix axis.b a left-handed antiparallel double-helix with 12 bp/turn formed fromalternating pyrimidine-purinesequences.c a right-handed antiparallel double helix with 11 bp/turn and bases tilted with respect to the helix axis.d a globular structure formed by short intramo

3、lecular helices formed in a single-strand nucleic acid.3. denaturation of double stranded dna involves. abreakage into short double-stranded fragments.b separation into single strands.c hydrolysis of the dna backbone.d cleavage of the bases from the sugar-phosphate backbone.4. which has the highest

4、absorption per unit mass at a wavelength of 260 nm? adouble-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 target of antibacterial drugs.section d - prokaryotic and eukaryoti

5、c chromatin structure1which of the following is common to both e. coli and eukaryotic chromosomes? athe dna is circular.b the dna is packaged into nucleosomes.c the dna is contained in the nucleus.8d the dna is negatively supercoiled.2a complex of 166 bp of dna with the histone octamer plus histone

6、hi is known as a . . .a nucleosome core.b solenoid.c 30 nm fiber.d chromatosome.3. in what region of the interphase chromosome does transcription take place? athe telomere.b the centromere.c euchromatin.d heterochromatin.4. which statement about cpg islands and methylation is not true? acpg islands

7、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 chromatin.5. which of the following is an example of highly-repetitive dna? aalu

8、element.b histone gene cluster.c dna minisatellites.d dispersed repetitive dna.section e - dna replication1. the number of replicons in a typical mammalian cell is . . . a40-200.b400.c1000-2000.d50000-100000.2. in prokaryotes,the lagging strand primers are removed by . . . a3 to 5 exonuclease.b dna

9、ligase.c dna polymerase i.d dna polymerase iii.3. the essential initiator protein at the e. coli origin of replication is . . . adnaa.b dnab.c dnac.d dnae.4. prokaryotic plasmids can replicate in yeast cells if they contain a cloned yeast. . . aorc.b cdk.c ars.d rna.section f - dna damage, repair an

10、d recombination(此章不考)1. per nucleotide incorporated, the spontaneous mutation frequency in e. coli is . . . a1 in 106.b1 in 108.c1 in 109.d1 in 1010.2. the action of hydroxyl radicals on dna generates a significant amount of . . . apyrimidine dimmers.b 8-oxoguanine.c o6- methylguanine.d 7-hydroxymet

11、hylguanine.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.c ap endonuclease.d 3 to 5 exonuclease.4. the excision repair of uv-induced dna damage is defective in individuals suffering fro

12、m .a hereditary nonpolyposis colon cancer.b crohns disease.c classical xeroderma pigmentosum.d xeroderma pigmentosum variant.section k - transcription in prokaryotes1. which two of the following statements about transcription are correct? arna synthesis occurs in the 3 to 5 direction.b the rna polym

13、erase enzyme moves along the sense strand of the dna in a 5 to 3direction.c the rna polymerase enzyme moves along the template 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 r

14、na chain.f the rna polymerase adds deoxyribonucleotides to the 3 end of the growing rna chain.2. which one of the following statements about e. coli rna polymerase is false? athe holoenzyme includes the sigma factor.b the core enzyme includes the sigma factor.c it requires mg2+ for its activity.d it

15、 requires zn2+ for its activity.3. which one of the following statements is incorrect?a there are 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 st

16、reptolydigins inhibit transcription elongation.f heparin is a polyanion, which binds to the subunit.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 alw

17、ays a g.c the intervening sequence between the -35 and -10 sequences is conserved.d the sequence 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

18、of the following statements about transcription in e. coli is true?a loose binding of 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 puri

19、ne residue, with a being more common than g.d all promoters are inhibited by negative supercoiling.e terminators are often a-u hairpin structures.section l - regulation of transcription in prokaryotes1. which two of the following statements are correct?a the double stranded dna sequence that has the

20、 upper strand sequence 5- ggatcgatcc-3 is a palindrome.b the double stranded 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 repr

21、essor to allolactose reduces its affinity for the lac operator.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 pr

22、otein.b when glucose is present in the cell camp levels 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? athe

23、rna product of the trp operon is very stable.b the 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 regu

24、lated by the trp represso4. which two of the following 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

25、upstream of the trp operator sequence.d attenuation 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 stop

26、s formation of the terminator hairpin, resulting in transcriptional read-through into the trpe gene, when tryptophan is scarce.section m - transcription in eukaryotes1. which one of the following statements about eukaryotic rna polymerases i, ii and iii is false?a rna pol ii is very sensitive to -am

27、anitin.b rna pol ii is located in th nucleoplasm.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 a

28、s additional subunits， which are unique 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?

29、arna pol i transcribes the genes 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 gen

30、e clusters are known as nucleolar 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

31、 upstream part of the core 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 stateme

32、nts about rna pol iii 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 transc

33、ription factor on its own.e in humans 5s rrna genes are arranged in a single cluster of 2000 copies.section 0 - rna processing and rnps1. which ribonucleases are involved in producing mature trna in e. coli? arnases a, d, e and f.brnases d, e, f and h. crnases d, e, f and p. drnases a, d, h and p.2.

34、 most eukaryotic 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 cleavage and po

35、lyadenylation 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 spliceosome removes the exon

36、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 and then the tri-snrnp, u4, us and u6 can

37、 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 trna1. which of the following list of features correctly apply to the genetic code? atriplet dege

38、nerate 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 of the following statements about trnas is false?a

39、 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 andmosme.c trnas have a common l-shaped tertiary structure with three nucleotides at one end able to base pair with an anticodon on a

40、 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. ajoins amp to the 3-end of the trna.b is a two step reaction.c joins a

41、ny 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 todistinguish between them.e joins amp to the amino acid to produce an intermediate.f releases ppi in the second step.section q - protein synthesis1. wh

42、ich statement about the codon-anticodon interaction is false? ait is antiparallel and can include nonstandard base pairs.binosine in the 5 -anticodon position can pair with a, c or u in the 3-codon position cinosine in the 3-anticodon position can pair with a, c or u in the 5-codon position. da is n

43、ever 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 the initiator trna binds to the shine-dalgarno sequence.b three initiation factors are involved and if2 binds to g

44、tp.c the intermediate containing if1, if2, if3, initiator trna and mrna is called the 30s initiation complex.d binding of the 50s subunit releases if1, if2, gmp and ppi.e the initiation process is complete when the 70s initiation complex is formed which contains the initiator trna in the a site of the ribosome and an empty p site.3. which statement about elongation of protein synthesis in prokaryotes is false?a elongation can be divided into three steps: peptidyl-trna delivery peptide bondformation and translocation.b the peptidyl transferas