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第三单元 基因和染色体-2（基因概念的多样性） Chapter 2 Gene and Chromome _ Test
1、 Watson & Crick won the noble prize in 1962 for their discoveries concerning:
A:the interaction between tumour viruses and the genetic material of the cell
B:the mobile genetic elements
C:the molecular structure of nucleic acids
D:the invention of the PCR method
答案: the molecular structure of nucleic acids
2、 Most of the stability of the double-stranded DNA structure is the result of
A: hydrogen bonding between purines.
B:the phosphodiester backbone.
C:the angle of the planes of the bases with respect to the helix axis.
D:the stacking interactions between base pair.
答案: the stacking interactions between base pair.
3、 It is easier to melt DNA richer in AT than GC because
A:it is more heat sensitive.
B:there is one less hydrogen bond in an AT base pair
C: the helix pitch is longer in AT rich regions.
D:All of the three statements.
答案: there is one less hydrogen bond in an AT base pair
4、 As B-DNA is gradually heated, the absorbance at 260 nm
A:increases.
B:decreases.
C:stays the same.
D: It is unpredictable.
答案: increases.
5、 What are the target and the probe of the Southern blotting？
A:DNA, DNA
B:RNA, RNA
C:Protein, antibody
D: None of the above.
答案: DNA, DNA
6、 Supercoiling of pure circular DNA is a result of __.
A:underwinding or overwinding of the helix
B:the long length of the strands
C:the lack of associated histones
D:the activity of exonucleases
答案: underwinding or overwinding of the helix
7、 Which of the following is an example of highly-repetitive DNA?
A:Globin gene family
B:Histone gene cluster
C:Minisatellite DNA
D:rDNA gene family
答案: Minisatellite DNA
8、 Histones are found in close association with DNA. Which of the following statements is incorrect?
A:A nucleosome core is composed of ~146 bp of DNA and a histone octamer.
B:Histone H1 binds to linker DNA.
C:There are only four types of histones.
D:Nucleosomes are evenly distribution within chromatin.
答案: There are only four types of histones.
9、 DNA wraps around an octamer of histones to form bead-like structures called __.
A:nucleoids
B:nucleosomes
C:nucleoli
D:chromatids
答案: nucleosomes
10、 What is the approximate diameter of a chromatin fiber?
A:3 nm
B:30 nm
C:300 nm
D:3 mm
答案: 30 nm
11、 What is the order of packaging of chromatin in eukaryotic cells from smallest to largest size?
A:double-helix → solenoid螺线管 → nucleosome → chromosome
B:double-helix → chromatin → solenoid → chromosome
C:single-stranded DNA → chromatin → histones → chromosome
D:double-helix → nucleosomes → solenoid → chromosome
答案: double-helix → nucleosomes → solenoid → chromosome
12、 How might mitochondrial DNA be distinguished from eukaryotic nuclear DNA?
A:Mitochondrial DNA is in the Z conformation, nuclear DNA is in the B conformation.
B:Mitochondrial DNA is methylated, nuclear DNA is not.
C:Nuclear DNA is linear, mitochondrial DNA are circular.
D:They cannot be distinguished and must be clearly separate during purification
答案: Nuclear DNA is linear, mitochondrial DNA are circular.
13、 Which of the following statements is not correct concerning to the prokaryotic genome and eukaryotic genome?
A:There are many non-coding DNAs in eukaryotic genome.
B:DNA are almost naked in prokaryotes.
C:There are many operons in eukaryotic genome.
D:Prokaryotic genome is a single circular DNA molecule.
答案: There are many operons in eukaryotic genome.
14、 Which does not apply to most bacterial DNA?
A:Circular.
B:Relaxed.
C:Not packed into nucleosomes.
D:Supercoiled.
答案: Relaxed.
15、 In a nucleic acid molecule, nucleotides are joined into a polymer by the __ phosphodiester bonds.
A:2′,3′
B:2′,4′
C:3′, 4′
D:3′, 5′
答案: 3′, 5′
16、 All genomes are composed of DNA.
A:正确
B:错误
答案: 错误
17、 The two strands of double-stranded DNA have the same content of each of the bases A, T, G and C.
A:正确
B:错误
答案: 错误
18、 The supercoiling of double-stranded circular DNA can be removed by cleaving a single phosphodiester bond on only one strand (nick).
A:正确
B:错误
答案: 正确
19、 Prokaryotic DNA is organized into protein-DNA structures called nucleoids.
A:正确
B:错误
答案: 正确
20、 Histone H1 is part of the histone octamer.
A:正确
B:错误
答案: 错误
21、 Heterochromatin make up most of the genome.
A:正确
B:错误
答案: 错误
22、 The maximum C-value is always greater than minimum C-value in an organism.
A:正确
B:错误
答案: 错误
第四单元 DNA的复制 Chapter 3 DNA replication -test
1、 All of the following statements about DNA replication in prokaryotes are true except:
A:DNA replication is conservative.
B:DNA synthesis occurs in the 5’ to 3’ direction.
C:Requires a 3’OH to initiate replication which is provided by an RNA primer.
D: DNA replication initiate from specific origin.
答案: DNA replication is conservative.
2、 E. coli is grown on a medium containing 15N for a long time. Cells were then transferred to medium containing only normal 14N. DNA samples were obtained for analysis after three rounds of replication and centrifuged on a density gradient. How many bands can we see?
A:One with DNA containing both 15N and 14N.
B:Two, one with DNA containing only 15N and one with DNA containing only 14N.
C:Two, one with DNA containing both 15N and 14N and one with DNA containing only 14N.
D:Three, one with DNA containing only 15N, one with DNA containing both 15N and 14N and one with DNA containing only 14N.
答案: Two, one with DNA containing both 15N and 14N and one with DNA containing only 14N.
3、 Which DNA polymerase is most responsible for chain elongation in E. coli?
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