Section C - properties of nucleic acids
1．The quence 5'-AGTCTGACT-3' in DNA is equivalent to which quence 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 英语学习计划表 a right-handed antiparallel double helix with 10 bp/turn and bas lying perpendicular to the helix axis.
B a left-handed antiparallel double-helix with 12 bp/turn formed from alternating pyrimidine-purine quences.
C a right-handed antiparallel double helix with 11 bp/turn and bas tilted with respect to the 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 paration into single strands.
C hydrolysis of the DNA backbone.
D cleavage of the bas 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 ostrava 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 eukaryotic chromatin structure
1．Which of the following is common to both E. coli and eukaryotic chromosomes?
A the DNA is circular.
B 歌舞青春男女主角 the DNA is packaged into nucleosomes.
C the DNA is contained in the nucleus.
D the DNA is negatively supercoiled.
2．A complex of 166 bp of DNA with the histone octamer plus histone HI is known as a . . .
A ason怎么读 nucleosome core.
B solenoid.
C 30 nm fiber.
D chromatosome.
3．In what region of the interpha chromosome does transcription take place?
A the telomere.
B the centromere.
C euchromatin.
D abort heterochromatin.
4． Which statement about CpG islands and methylation is not true?
A CpG islands are particularly resistant to DNa 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?
A Alu element.
B histone gene cluster.
C DNA minisatellites.
D disperd repetitive DNA.
Section E - DNA replicationpolly
1．The number of replicons in a typical mammalian cell is . . .
A 40-200.
B 400.
C 1000-2000.
D 50000-100000.
2. In prokaryotes,the lagging strand primers are removed by . . .
A 3' to 5' exonuclea.
avenue怎么读B DNA liga.
C DNA polymera I.
棱台D DNA polymera III.
3. The esntial initiator protein at the E. coli origin of replication is . . .
A DnaA.
B DnaB.
单曲循环英文
tripC DnaC.
D DnaE.
4. Prokaryotic plasmids can replicate 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 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 ba is nicked by . . .
AMutH endonuclea.
BUvrABC endonuclea.
CAP endonuclea.
D3' to 5' exonuclea.
4. The excision repair of UV-induced DNA damage is defective in individuals suffer
ing from ...
A hereditary nonpolyposis colon cancer.
B Crohn's dia.
C classical xeroderma pigmentosum.
D xeroderma pigmentosum variant.
Section K - Transcription in 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 polymera enzyme moves along the n strand of the DNA in a 5' to 3' direction.
C the RNA polymera 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 polymera adds ribonucleotides to the 5' end of the growing RNA chain.
