Gene Manipulation Questions and Answers for Entrance exams focuses on “Gene Manipulation in Gram – Negative Bacteria”.
1. What is required to clone DNA in non-enteric bacteria?
A. Enzymes
B. PCR
A. Plasmid
D. Phage
Answer: C
Clarification: For cloning in non-enteric bacteria, bacteria other than E. coli, a plasmid cloning vector is required which can replicate in the selected organism.
2. In Gram-negative bacteria other than E.coli, it is used as a ___________
A. Hybrid vector
B. Main host
A. Inhibitor
D. Intermediate host
Answer: D
Clarification: Under normal circumstances, E.coli is used as an intermediate host for a transformation of the ligation mix and screening of the recombinants.
3. The vector used for cloning in non-enteric bacteria must also be able to replicate in E.coli.
A. True
B. False
Answer: A
Clarification: Since E. coli is used as an intermediate host in cloning of the non-enteric bacteria, the vector used must also be able to replicate in E. coli.
4. If the selectable markers are not expressed in the new host, then ____________ is necessary.
A. Helper phage
B. Manipulations
A. Temperature control
D. Recombination
Answer: B
Clarification: If the selectable markers are not expressed in the new host, then extensive manipulations may be necessary to enable detection of transformants.
5. RSF1010 specifies resistance to how many antimicrobial agents?
A. 1
B. 2
A. 3
D. 4
Answer: B
Clarification: Plasmid RSF1010 is a multicopy replicon which specifies resistance to two antimicrobial agents, sulfonamide and streptomycin.
6. What is the length of DNA of RSF1010?
A. 4684 bp
B. 6684 bp
A. 7684 bp
D. 8684 bp
Answer: D
Clarification: The plasmid DNA of RSF1010 is 8684 base pairs in length and has been completely sequenced. A detail physical and functional map has been constructed.
7. How many PstI sites in plasmid RSF1010?
A. 1
B. 2
A. 3
D. 4
Answer: B
Clarification: There are two PstI sites in RSF1010, about 750 base pairs apart, which flank the sulfonamide resistance determinant. PstI is a restriction enzyme.
8. How many unique cleavage sites are located within the antibiotic resistance determinants of plasmid RSF1010?
A. 0
B. 2
A. 4
D. 6
Answer: A
Clarification: None of the unique cleavage sites is located within the antibiotic resistance determinants and none is particularly useful for cloning.
9. Insertion of DNA fragment between PstI sites ____________ the resistance determinant.
A. Activates
B. Inactivates
A. Weakens
D. Removes
Answer: B
Clarification: Insertion of DNA fragment between the PstI sites inactivates both the antibiotic resistance determinants. Hence a new selectable marker has to be used.
10. Which resistance is lost if DNA is inserted in EcoR1 or BstEII sites?
A. Sulphonamide
B. Alcohol
A. Ampicillin
D. Streptomycin
Answer: D
Clarification: Although the sites EcoR1 and BstII lie outside the coding regions of the gene, streptomycin resistance is lost if a DNA fragment is inserted at these sites.
11. What is the size of IncP alpha plasmids?
A. 20 kb
B. 40 kb
A. 60 kb
D. 80 kb
Answer: C
Clarification: The IncP alpha plasmids: R18, R68, RK2, RP1 and RP4 are 60 kilobases in size and their genomes have been completely sequenced.
12. IncP alpha plasmids are smaller in size than IncPbeta plasmids.
A. True
B. False
Answer: B
Clarification: The IncP alpha plasmids are 60 kilobases in size whereas IncP beta plasmids are 52 kilobases in size. Both have been developed as conjugative vectors.
13. IncP alpha and InP beta are _________ host range vectors.
A. Overlapping
B. Narrow
A. Broad
D. Specific
Answer: C
Clarification: Mini versions of the IncP-group plasmids such as IncP alpha and IncP beta have been developed as conjugative broad host range vectors.
14. P-group plasmids are not widely used as vectors because of their _____________
A. Big size
B. Small size
A. Toxicity
D. Host range
Answer: A
Clarification: Much is known about the genome of P-group plasmids such as their restriction site locations and genes carried. Despite this, they are not widely used as vectors because of their large size which makes manipulations difficult.
15. Blanty’s group of mini-IncP plasmids has a maximum size of _______ kb.
A. 1
B. 3
A. 5
D. 7
Answer: D
Clarification: Blanty’s group of mini-IncP plasmids as vectors was created in 1997. Their vectors are only 4.8 to 7.1 kb in size but can still be maintained in a wide range of gram-negative bacteria.
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