This set of Vector Biology written test Questions & Answers focuses on “Vectors for Mammals – 12”.
1. What does the replicase protein of alphaviral vectors produce?
b) Complementary strand
c) Daughter genome
d) Host genome
Explanation: The replicase protein produces a negative-sense complementary strand, which in turn acts as a template for the production of full-length daughter genomes.
2. The negative strand produced by replicase protein contains no internal promoter.
Explanation: The negative strand contains an internal promoter which allows the synthesis of a subgenomic positive sense RNA containing the capsid polyprotein gene.
3. Replication competitive vectors contain an additional __________
b) Subgenomic promoter
d) Double promoter
Explanation: Replication-competent vectors have been constructed in which an additional subgenomic promoter is placed either upstream or downstream of the capsid polyprotein gene.
4. Introduction of foreign DNA downstream of the subgenomic promoter produces two distinct _________________
Explanation: If foreign DNA is introduced downstream of the subgenomic promoter, the replicase protein produces two distinct RNAs, one corresponding to the transgene.
5. In insertion alphaviral vectors, the capsid polyprotein is replaced by __________
Explanation: Insertion vectors tend to be unstable and have been largely superseded by replacement vectors in which the capsid polyprotein is replaced by a transgene.
6. A strong enhancer of protein synthesis in the Sindbis vector increases ______________
a) Recombinant protein
b) Recombinant DNA
d) Genomic size
Explanation: The first 120 b of Sindbis and SFV structural polyprotein genes includes a strong enhancer of protein synthesis which increases the yield of recombinant protein.
7. Why is the enhancer region included in many vectors based on alphaviruses?
a) Expression of protein on N-terminus
b) Expression of protein on P-terminus
c) Expression as a fusion protein
d) To decrease expression
Explanation: In many vectors, the enhancer region is included so that the foreign gene is expressed as an N-terminal fusion protein.
8. pSinRep5 is a ________ vector marketed by Invitrogen.
a) Sindbis replicon
Explanation: A versatile Sindbis replicon vector, pSinRep5 vector is a plasmid containing bacterial backbone elements along with several other genes.
9. Which of the following promoters is used in pSinRep5 vector?
Explanation: There is an SP6 promoter upstream of the replicase genes and the expression cassette for generating full length in vitro transcripts.
10. What is the function of downstream restriction sites of the pSinRep5 vector?
c) DNA replication
Explanation: There is a second set of restriction sites downstream from the polylinker, allowing the vector to be linearized prior to in vitro transcription.
11. Which of the following is a standard eukaryotic promoter?
Explanation: The entire alphavirus genome can be placed under the control of standard eukaryotic vector SV40 and cells can then be transfected with DNA.
12. Transduction is a more suitable procedure for gene therapy using alphavirus vectors.
Explanation: Transduction is a more suitable delivery procedure for gene therapy applications, using alphaviral vectors along with defective helper virus.
13. Vaccinia is a type of ___________
b) Hybrid vector
Explanation: Vaccinia virus is closely related to variola virus, the agent responsible for smallpox. Worldwide vaccination of this virus led to the elimination of smallpox.
14. What is the unusual property associated with poxviruses?
a) Small size
b) Replication mechanism
c) Expression mechanism
d) Replication site
Explanation: Unusually for a DNA virus, the poxviruses replicate in the cytoplasm rather than the nucleus. The virus packages and encodes its DNA all by itself.
15. What is the approximate size of poxviruses?
a) 100 kb
b) 200 kb
c) 300 kb
d) 10 kb
Explanation: The poxviruses have a complex structure and a large double-stranded linear DNA genome. The virus packages and encodes its DNA all by itself.
Sanfoundry Global Education & Learning Series – Vector Biology & Gene Manipulation.
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