Download 分子生物學小考(一) 範圍ch3~ch7

分子生物學小考(二)
範圍 ch8~ch
單選題(每題 2 分, 總分 30 分)
1. The poly(A) tail of eukaryotic mRNA is approximately
(A) 1000
(B) 250
(C) 100
(D) 25
nucleotides in length
(E) 5
2. Which of the following is the best way to determine the base content of DNA?
(A) gel electrophoresis
centrifugation
(B) spectrophotometry
(C) x-ray diffraction
(D) density gradient
(E) deoxyribonuclease treatment
3. In which of the following situations is a silent mutation least likely?
(A) change in a sequence in the 5’ UTR.
sequence in an exon.
(B) change in a sequence in the 3’ UTR.
(D) change in the sequence in the promoter.
(C) change in a
(E) change in a sequence in an
intron.
4. In prokaryotes, environmental sensing frequently involves regulatory proteins (two-component system)
that sense and respond to changes in surroundings. These two-component systems may involve which of the
following?
I. Protein phosphorylation
(A) I only
II. Transcriptional regulation
(B) II only
(C) III only
III. Membrane proteins
(D) II and III only
(E) I, II, and III
5. Which of the following nucleotides is not normally occurring?
(A) 3’-dAMP
(B) 2’-dAMP
(C) 3’,5’-cyclicAMP
(D) 5’-AMP
(E) dTTP
6. The genetic code is said to be degenerate. This means, that
(A) each codon codes for more than one amino acid
(B) each anticodon can interact with many different triplet sequences in the mRNA
(C) many of the amino acids are coded for by different codons
(D) the code is universally used by virtually all species
7. Which of the following is not a mobile DNA element?
(A) transposon
(B) long terminal repeats (LTR)
insertion sequence (IS)
(C) long interspersed elements (LINES)
(E) Ac element
8. True statements about retrotransposons include which of the following?
I. They replicate through the RNA intermediate.
II. They utilize reverse transcriptase for replication.
III. They may contain introns.
(A) I only
(B) III only
(C) I and III only
(D) II and III only
(E) I, II and III
(D)
9. All of the following components of a retrovirus are encoded by the viral genome EXCEPT
(A) matrix proteins
(B) viral RNAs
(C) capsid proteins
(D) envelope lipids
(E)
receptor-binding proteins
10. Some viruses have increased the coding potential of their genome by
(A) integrating into the host genome
splicing sites
(B) using host ribosomes for translation
(D) using a degenerative triplet code
(C) using alternative
(E) covalently linking a protein to the genome
11. The recognition site of the restriction endonuclease AvaI is CPyCGPuG, where Py is any pyrimidine and
Pu is any purine. What is the expected average distance, in nucieotide pairs, between AvaI cleavage sites in a
random DNA sequence?
(A) 4,096
(B) 1,024
(C) 682
(D) 64
(E) 6
12. An E. coli strain lacking DNA polymerase I would be deficient in DNA
(A) repair
(B) methylation
(C) splicing
(D) degradation
(E) transcription
13.Indicate the order in which the following steps occur in the production of a mature mRNA.
(A) initiation of transcription, splicing, addition of 5’ cap, addition of poly(A) tail, transport to cytoplasm
(B) initiation of transcription, addition of 5’ cap, splicing, addition of poly(A) tail, transport to cytoplasm
(C) initiation of transcription, addition of poly(A) tail, addition of 5’ cap, splicing, transport to cytoplasm
(D) initiation of transcription, addition of 5’ cap, addition of poly(A) tail, splicing, transport to cytoplasm
(E) transport to cytoplasm, addition of 5’ cap, addition of poly(A) tail, splicing, initiation of transcription
14. Which one of the following definition of terminology is not correct?
(A) "Transcription Factor" is a protein that assists RNA polymerase to recognize promoters
(B) "Transcription Repressor" is a sequence upstream of promoter that has negative effects on gene
(C) "Transcription Insulator" is a sequence that acts as a neutral barrier for nearby genes
(D) "General Transcription Factor" is a transcription factors requires for the basal level of transcription
(E) "Architectural transcription factor" is a transcription factor that changes the shape of promoter region but
no enhancement of transcription
15. Which of the following statements is not true about the cro gene?
(A) It must be stimulated during the lylic cycle.
(B) Its product represses σ repressor activity.
(C) It is adjacent to the cII gene.
(D) It codes for a repressor of the cI gene.
(E) cro activation is necessary for lysogeny.