Vector Biology MCQs focuses on “Vectors and Cloning in Gram – Positive Bacteria – 2”.
1. All B. subtilis vectors replicate by _______________ mechanism.
A. Translation
B. Meiosis
A. Mitosis
D. Rolling circle
Answer: D
Clarification: All the B. subtlis vectors replicate by the rolling circle mechanism. Nearly every step in the process digresses from its usual function, thus effecting rearrangements.
2. ____________ DNA is generated during rolling circle mechanism.
A. Double stranded
B. Mutated
A. Single stranded
D. Wild type
Answer: C
Clarification: Single-stranded DNA is generated during rolling circle mechanism. It is known to be a reactive intermediate in every recombination process.
3. Vectors replicating by ____________ mechanism are more stable than those replicating by rolling circle mechanism.
A. Alpha
B. Theta
A. Beta
D. Gamma
Answer: B
Clarification: If structural instability is a consequence of rolling circle mechanism, then vectors which replicate by the alternative theta mechanism could be more stable.
4. Plasmid Pamb1 is derived from _____________
A. B. subtilis
B. Streptococcus
A. Yeast
D. Bacillus
Answer: B
Clarification: Janniere et al. (1990) have studied two potentially useful plasmids, Pamb1 which is a large natural plasmid derived from Streptococcus.
5. Replication of Pamb1 and Ptb19 does not lead to accumulation of _______________
A. Single-stranded DNA
B. Toxins
A. Genes
D. Nucleases
Answer: A
Clarification: Replication of Pamb1 and Ptb19 does not lead to accumulation of detectable amounts of single-stranded DNA, whereas the rolling-circle mode of replication does.
6. Classical E.coli vectors replicate via theta-like structures.
A. True
B. False
Answer: A
Clarification: The classical E. coli vectors, which are derived from plasmid ColE1, all replication via theta-like structures and not the rolling-circle mechanism.
7. All the series of cloning vectors developed from PAMB1 carry repE and copF which is a __________
A. Promoter
B. Regulator
A. Gene
D. Protein
Answer: B
Clarification: All the vectors developed from PAMB1 carry a gene essential for replication, repE, and its regulator copF. These are two important constituents.
8. CopF of PAMBI-derived vectors can be deactivated by inserting linker into ____________
A. Promoter
B. Inducer
A. KpnI site
D. Tol site
Answer: C
Clarification: The copF gene of PAMB1-derived vectors can be deactivated by inserting a linker into a unique Kpn1 site. Deactivation of copF leads to increase in the plasmid copy number per cell.
9. Deactivation of copF gene leads to _________
A. Increase in cell size
B. Increase in plasmid copy number
A. Decrease in cell size
D. Decrease in plasmid copy number
Answer: B
Clarification: The copF gene of PAMB1-derived vectors can be deactivated by inserting a linker into a unique Kpn1 site. Deactivation of copF leads to increase in the plasmid copy number per cell.
10. The original low copy number state of the PAMB1-derived vectors can be restored by _________ of the linker.
A. Induction
B. Deletion
A. Deactivation
D. Removal
Answer: D
Clarification: The copF gene of PAMB1-derived vectors can be deactivated by inserting a linker into unique Kpn1 site. Deactivation of copF leads to increase in the plasmid copy number per cell.
11. Poyart and Trie-Cuot constructed a shuttle vector based on PAMB1 for construction of ____________
A. Transcriptional fusions
B. Translational fusions
A. Biotherapeutics
D. Fusions
Answer: A
Clarification: Poyart and Trie-Cuot constructed a shuttle vector based on PAMB1 for construction of transcriptional fusions, it can be conjugally transferred between E. coli and a wide range of gram-positive bacteria.
12. Compared with E.coli, B. subtilis has additional requirements, it can _________ the expression of genes from Gram-negative organisms in ones that are Gram-positive.
A. Induce
B. Increase
A. Prevent
D. Decrease
Answer: C
Clarification: Compared with E.coli, B. subtilis has additional requirements for efficient transcription and translational and this can prevent the expression of genes from Gram-negative organisms in ones that are Gram-positive.
13. Which of the following is the principal sigma factor?
A. Sigma A
B. Sigma B
A. Sigma C
D. Sigma D
Answer: A
Clarification: The number of sigma factors is different in each of the various genera but the principal sigma factor is sigma A. The composition of the core RNA polymerase is the same in most general.
14. In B. subtilis many promoters contain essential ________ motif.
A. AGAG
B. TGTG
A. GGGG
D. GCGC
Answer: B
Clarification: In B. subtilis many promoters contain an essential TGTG motif upstream of the -10 region. Mutations of this region reduce promoter strength.
15. The TGTG motif is located at ______ region.
A. -10
B. -16
A. -20
D. -25
Answer: B
Clarification: In B. subtilis many promoters contain an essential TGTG motif upstream of the -10 region. Mutations of this region reduce promoter strength.
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