Category: Vector Biology Objective Questions

Advanced Vector Biology Questions and Answers focuses on “Vectors and Cloning in Gram – Positive Bacteria – 3”.

1. The promoters of B. subtilis vectors have conserved polyA and ________ tails.
A. PolyT
B. PolyC
A. PolyG
D. PolyA
Answer: A
Clarification: The promoters also have conserved polyA and polyT tracts upstream of the -35 region. Some promoters also have a -16 region.

2. Ribosomes from _________ recognize only homologous mRNA.
A. E. coli
B. B. subtilis
A. Yeast
D. Bacteriocins
Answer: B
Clarification: E. coli ribosomes can support protein synthesis when directed by mRNA from a range of Gram-positive and Gram-negative organisms, whereas Ribosomes from B. subtilis recognize only homologous mRNA.

3. The selectivity of ribosomes of B. subtilis is due to the lack of ________
A. Inducer
B. Promoter
A. Protein S1
D. Repressor
Answer: C
Clarification: Ribosomes from B. subtilis recognize only homologous MRNA. This is because they lack a counterpart of the largest E. coli Ribosomal protein.

4. Which of the following does not lack MRNA selectivity?
A. Streptococcus
B. Clostridium
A. E. coli
D. Lactobacillus
Answer: C
Clarification: Few gram-positive bacteria such as staphylococcus, streptococcus, clostridium, and lactobacillus, lack S1-equivalent E.coli protein and therefore exhibit MRNA selectivity.

5. The role of S1 is to bind ________ non-specifically.
A. MRNA
B. RNA
A. DNA
D. CDNA
Answer: B
Clarification: The role of S1 is to bind RNA non-specifically and bring it to the decoding site of the 30S subunit, where proper positioning of the Shine-Dalgarno sequence and initiation codon signals can take place.

6. When was the Spac system for low-GC hosts developed?
A. 1990
B. 1984
A. 1963
D. 1936
Answer: B
Clarification: The first controlled expression system to be used in B. subtilis was the Spac system, developed by Yansura and Henner in 1984.

7. Which gene of E. coli is contained in the Spac system?
A. Tol
B. Amp
A. LacI
D. Gal
Answer: C
Clarification: The first controlled expression system to be used in B. subtilis was the Spac system. This consists of the E. coli lacI gene and the promoter of phage SPO-1.

8. A promoter from which phage is incorporated in the Spac system?
A. Lambda
B. M13
A. Prophage
D. SPO-1
Answer: D
Clarification: The first controlled expression system to be used in B. subtilis was the Spac system. This consists of the E. coli lacI gene and the promoter of phage SPO-1.

9. E. coli T7 system is successfully implemented in B. subtilis.
A. True
B. False
Answer: A
Clarification: E. coli T7 system is implemented in B. subtilis by inserting the T7 RNA polymerase gene into the chromosome under the control of the Xylose-inducible promoter and cloning the gene of interest, coupled to T7 promoter, on a B. subtilis vector.

10. The promoter used in T7 system is inducible by which of the following?
A. Xylose
B. Galactose
A. Lactose
D. Fructose
Answer: A
Clarification: E. coli T7 system is implemented in B. subtilis by inserting the T7 RNA polymerase gene into the chromosome under the control of the Xylose-inducible promoter and cloning the gene of interest, coupled to T7 promoter, on a B. subtilis vector.

11. Expression of a heterologous gene in the T7 system is ____________
A. Easy
B. Difficult
A. Not possible
D. Costly
Answer: A
Clarification: Expression of a heterologous gene in the T7 expression system can be made simpler by putting it directly under the control of the promoter.

12. Other than B. subtilis, the T7 expression system can also be used in __________
A. Lactobacillus
B. Yeast
A. Fungi
D. Agrobacterium
Answer: A
Clarification: A xylose inducible system has also been developed in lactobacillus and staphylococci. Many different controllable promoters are available.

13. In the phi-31 system of L. lactis, _________ vector is used.
A. Hybrid
B. Mammalian
A. Low copy number
D. High copy number
Answer: C
Clarification: In the phi-31 system of L. lactis, the gene of interest is placed under the control of a phage middle promoter inserted in a low copy number vector carrying the phage region ori.

14. In the phi-31 system of L. lactis, gene of interest is placed under the control of _____________ promoter.
A. Weak
B. Strong
A. End
D. Middle
Answer: D
Clarification: In the phi-31 system of L. lactis, the gene of interest is placed under the control of a phage middle promoter inserted in a low copy number vector carrying the phage region ori.

15. Following infection with phi-31, __________ increases.
A. Copy number
B. Mortality rate
A. Size
D. Protein production
Answer: A
Clarification: Following infection of the host cell with phi-31, the plasmid copy number rapidly increases and this is followed by expression from the phage promoter.

To practice advanced questions and answers on all areas of Vector Biology, .

Vector Biology Assessment Questions and Answers focuses on “Vectors for Mammals – 6”.

1. Agrobacterium tumefaciens can transfer DNA to animal cells.
A. True
B. False
Answer: A
Clarification: A. tumefaciens and its close relatives have been used for over 20 years to generate transgenic plants. More recently, it has been shown that A. tumefaciens can transfer DNA to cultured human cells.

2. Which of the following is an artificial form of bactofection?
A. Transduction
B. Protoplast fusion
A. Bolistics
D. Electroporation
Answer: B
Clarification: The protoplast fusion technique can be regarded as a highly artificial form of bactofection, but the amount of human intervention required distinguishes the technique.

3. In the cases of Salmonella species, lysis occurs in the __________
A. Outside the phagocytic vesicle
B. Inside the phagocytic vesicle
A. In lymphatic system
D. In nucleus
Answer: B
Clarification: In the case of Salmonella species, lysis occurs in the phagocytic vesicle, while for other species lysis occurs after the bacterium has escaped from the vesicle.

4. Which of the following occurs in DNA transfer by A. Tumefaciens?
A. Cell lysis
B. Conjugation
A. Infection
D. Myeloma
Answer: B
Clarification: A. tumefaciens transfers DNA to mammalian cells without invading them. Transfer occurs by attachment to the outside of the cell followed by conjugation.

5. Pilus helps in the transfer of DNA through a process of ___________
A. Transduction
B. Transfection
A. Conjugation
D. Transformation
Answer: C
Clarification: In A. tumefaciens, transfer occurs by attachment to the outside of the cell followed by conjugation. It is a process of transfer of DNA through a conduit called a pilus, which is assembled by the bacterial cell.

6. Which is an important principle in gene transfer using live bacteria?
A. Amplification
B. Attenuation
A. Lysis
D. Phagocytosis
Answer: B
Clarification: An important principle in the use of live bacteria as invasive gene-transfer vehicles is that they must be attenuated.

7. What would happen if attenuated bacteria are not used for mammalian gene transfer?
A. Cell death
B. Tumor
A. Proliferation
D. Unsuccessful gene transfer
Answer: A
Clarification: The gene transfer system exploits the natural ability of the bacteria to infect and subvert the activity of eukaryotic cells. Without attenuation, the bacteria would multiply and destroy the host cells.

8. Which of the following is a technique of bacterial attenuation?
A. Auxotrophic mutants
B. Removal of cell wall
A. Protoplast fusion
D. Conjugation
Answer: A
Clarification: Attenuation is achieved in several ways. One way is to use auxotrophic mutants that are bacterial strains that are unable to manufacture essential molecules.

9. AroA mutants are unable to synthesize _____________
A. Amino acids
B. Homeotic genes
A. Vitamins
D. Aromatic compounds
Answer: D
Clarification: AroA mutants are unable to synthesize aromatic amino acids and Salmonella typhimurium and Shigella flexneri strains carrying this mutation have been used for gene transfer.

10. Inducible autolysis is a technique for attenuation.
A. True
B. False
Answer: A
Clarification: The bacteria can be engineered so that they undergo inducible autolysis. Attenuation can be achieved by induced suicide, introducing an autolysin-encoding gene that is activated once the bacterium is inside the host cell.

11. Attenuation of ‘Listeria Monocytogenes’ can be achieved by ___________
A. Auxotrophic strains
B. Autolysis
A. Gene knockout
D. Mutation
Answer: B
Clarification: There are no auxotrophic strains of Listeria monocytogenes, so attenuation is achieved by induced suicide. Autolysin-encoding gene is introduced.

12. Apart from the introduction of DNA into cultured cells, bacteria mediated gene transfer has also been used for ________
A. Recombinant protein production
B. Transgenic animal
A. In vivo gene transfer
D. In vitro gene transfer
Answer: C
Clarification: Bacteria mediated gene transfer has been used not only as general transfection method for the introduction of DNA into cultured cells but also as a high efficiency method for gene transfer in vivo.

13. Virus particles have a natural ability of ___________
A. Adsorbing on the cell surface
B. Proliferation
A. Inducing tumor
D. Inducing apoptosis
Answer: A
Clarification: Virus particles have a natural ability to adsorb to the surface of cells and gain entry, and this can be exploited to deliver recombinant DNA into animal cells.

14. Helper-independent vectors can _____________
A. Not Propagate
B. Propagate dependently
A. Propagate independently
D. Transduce the cell
Answer: C
Clarification: If the transgene is added to the genome, or if it replaces one or more genes that are non-essential for the infection cycle in the expression host being used, the vector is described as helper-independent because it can propagate independently.

15. What happens if an essential gene is replaced in a viral vector?
A. Helper dependent
B. Helper independent
A. Non-function
D. Loss of transfection ability
Answer: A
Clarification: If the transgene replaces an essential viral gene, this renders the vector helper-dependent so that missing functions must be supplied in trans.

To practice all areas of Vector Biology Assessment Questions, .

Vector Biology Questions and Answers for Freshers focuses on “Cloning Vectors for E.Coli – 4”.

1. Which of the following assertions is true in regard to a cosmid vector?
A. No plaques are produced
B. Lac-selection system is used
A. It can carry small DNA fragments
D. Origin of replication is taken from lambda
Answer: A
Clarification: The cosmid is a hybrid between lambda phage and a plasmid and only the cos sites in the whole construct of cosmid belong to the phage. Ampicillin and tetracycline resistance genes are taken from the plasmid, no plaque formation is observed.

2. What digestion pattern of the restriction endonucleases is followed while constructing recombinant molecule using a cosmid?
A. Partial digestion
B. Complete digestion
A. Single endonuclease digestion
D. Double endonuclease digestion
Answer: A
Clarification: Partial digestion of the cosmid vector molecules is done because total digestion will lead to small sized fragments which in turn will lead to difficulty in in-vitro packaging.

3. If cosmid vector infected cells are grown on an agar plate containing antibiotic, what type of colonies will grow?
A. Non-recombinants
B. Recombinants
A. Both non-recombinants and recombinants
D. Cells with self-ligated vectors
Answer: B
Clarification: Plating cosmid infected cells on agar and antibiotic plate will only give rise to recombinant colonies as only they possess the antibiotic resistance. Also, the non-recombinants will be too small to package into the phage coat.

4. Which vectors carry the longest foreign DNA fragments?
A. M13 based vectors
B. Lambda based vectors
A. Plasmids
D. Hybrid vectors
Answer: B
Clarification: The main use of all lambda based vectors is to clone DNA fragments that are too long to be handled by plasmid or M13 vectors. Lambda based vectors can take upto 40 kb of DNA.

5. What does an E.Coli genomic library contain?
A. Recombinant clones of genes
B. Genes in E.coli genome
A. Expressed genes
D. Protein products
Answer: A
Clarification: A genomic library is a set of recombinant clones that contains all of the DNA of the E.coli genome. Any desired gene can be withdrawn from the library and studied.

6. Which vectors are mostly used for creating genomic libraries?
A. Lambda phage vectors
B. M13 phage vectors
A. Plasmid vectors
D. Cosmid vectors
Answer: A
Clarification: Lambda phage vectors are the most suitable for creation of genomic libraries for E.coli and other prokaryotes because they can carry larger lengths of DNA fragments.

7. What is the main use of a Bacterial Artificial Chromosome (BAC. vectors?
A. E.coli protein expression
B. Human genomic library construction
A. E.coli genomic library construction
D. Stable transfection
Answer: B
Clarification: BAC vectors are specifically created to handle longer DNA inserts for the construction of human genomic libraries. BACs can handle inserts upto 300 kb in size, reducing the library size to just 30,000 clones.

8. BAC vectors are based on _________ plasmid.
A. R
B. F
A. Col
D. Trp
Answer: B
Clarification: BAC vectors are based on F plasmids which are the fertility plasmids responsible for the occurrence of genetic material transfer between two cells by means of conjugation. These are relatively large and have a higher capacity.

9. What are PACs?
A. Low capacity phage vector
B. High capacity phage vector
A. Plasmid vector
D. Phagemid vector
Answer: B
Clarification: P1 derived artificial chromosomes (PACs) are high capacity vectors that combine the features of P1 vectors and BAC vectors having a capacity of up to 300 kb.

10. Which type of vector is P1?
A. Phage
B. Plasmid
A. Cosmid
D. Phagemid
Answer: A
Clarification: P1 is a high capacity vector constructed from P1, which has the advantage over lambda of being able to squeeze 110 kb of DNA into its capsid structure.

11. Pjb8 is an example of __________ vector.
A. Cosmid
B. Phagemid
A. Hybrid
D. M13 bacteriophage
Answer: A
Clarification: Pjb8 is a cosmid vector constructed as a hybrid between a phage DNA molecule and a bacterial plasmid. Cos sites belong to the phage genome and all other genetic elements come from a plasmid.

To practice all areas of Vector Biology for Freshers, .

Gene Manipulation Interview Questions and Answers focuses on “Role of Bioinformatics in Gene Manipulation”.

1. When was the first database of protein sequences established?
A. 1940
B. 1950
A. 1960
D. 1970
Answer: C
Clarification: In 1960s, Margaret Dayhoff established the first database of protein sequences, a database that was published annually as a series of volumes entitled Atlas of Protein Sequence and Structure.

2. Which of the following was the first protein to be sequenced?
A. Pectin
B. Insulin
A. Lectin
D. Rhodopsin
Answer: B
Clarification: Bioinformatics was born when the first complete protein sequence was determined. This was bovine insulin sequenced between 1951 and 1955.

3. When was ‘Atlas of Protein Sequence and Structure’ published?
A. 1955
B. 1965
A. 1975
D. 1985
Answer: B
Clarification: By 1965, when the ‘Atlas of Protein Sequence and Structure’ was first published, there were more than 100 sequences in the scientific literature.

4. “Globins” is a family of ____________
A. Datasets
B. Genes
A. Proteins
D. Hosts
Answer: C
Clarification: Most of the sequences contained in ‘Atlas of Protein Sequence and Structure’ were redundant and were used to investigate sequence diversity between homologous proteins in large families such as the globins.

5. When was the first nucleotide sequence determined?
A. 1966
B. 1946
A. 1976
D. 1986
Answer: A
Clarification: The first nucleotide sequence to be determined was that of a yeast transfer-RNA by Madison in the year 1966. Most nucleotide sequences prior to about 1975 were from RNA molecules.

6. When was the first nucleotide sequence database developed?
A. 1942
B. 1972
A. 1982
D. 2002
Answer: C
Clarification: In 1982 there were enough DNA sequences to justify the establishment of the first nucleotide sequence database, GenBank.

7. By the end of 1982, what was the approximate number of sequences in GenBank?
A. 100
B. 200
A. 400
D. 600
Answer: D
Clarification: By the end of 1982, GenBank contained a grand total of 606 sequences. The database grew steadily until about 1994 when the genomics era really kicked in.

8. In 1994, the approximate number of sequences in GenBank rose to ____________
A. 200
B. 2000
A. 20000
D. 200000
Answer: D
Clarification: In 1994 the number of sequences in GenBank was just over 200,000. Two decades later, the figure stands at 30 million and shows no sign of slowing down.

9. Primary sequence databases are repositories for _______________
A. Nucleotide sequence
B. Protein sequence
A. Genome sizes
D. Host range
Answer: A
Clarification: The primary sequence databases are repositories for annotated nucleotide sequence data. These are the most important databases in molecular biology.

10. DDBJ is a _________________
A. Repository
B. Protein bank
A. Nucleotide sequence database
D. Secondary database
Answer: C
Clarification: DDBJ is the abbreviation of the DNA Databank of Japan, and is a primary database. New sequence data can be deposited with this databank.

11. The primary sequence databases are repositories for _______ sequence data.
A. Incomplete
B. Complete
A. Contaminated
D. Raw
Answer: D
Clarification: The primary sequence databases are repositories for raw sequence data derived directly from experiments and sequencing projects.

12. The dbEST is a subsidiary of ___________
A. EMBL
B. GenBank
A. DDBJ
D. SwissProt
Answer: B
Clarification: GenBank has a subsidiary called the dbEST, which is a database of ESTs. It has been instrumental in generating gene maps by in-silico analysis.

13. SWISS-PROT is a repository for ____________
A. Nucleotide sequences
B. Protein sequences
A. Vectors
D. Genome arrays
Answer: B
Clarification: The SWISS-PROT is not just a repository for protein sequences. Rather, it is a collection of confirmed protein sequences annotated with related information.

14. Curated data in a database means _________ data.
A. Actively managed
B. Duplicate
A. Incomplete
D. Raw
Answer: A
Clarification: The quality of data in a database like SWISS-PROT is very high because it is actively managed, that is the data is curated, making all the necessary information accessible.

15. TrEMBL consists of entries in the same format as SWISS-PROT.
A. True
B. False
Answer: A
Clarification: The less robust TrEMBL database consists of entries in the same format as those in SWISS-PROT, derived from the translation of all coding sequences in EMBL.

To practice all areas of Gene Manipulation for Interviews, .

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.

To practice MCQs on all areas of Vector Biology, .

Vector Biology Questions & Answers for Exams focuses on “Vectors for Mammals – 5”.

1. What is reporter genes used for?
A. To confirm transformation
B. To confirm transfection
A. To induce expression
D. To cease expression
Answer: A
Clarification: When controlled by a strong promoter, reporter genes are often used as markers to confirm stable or transient transformation.

2. What is “CAT”?
A. Repressor gene
B. Promoter
A. Reporter gene
D. Hybrid vector
Answer: C
Clarification: The first reporter gene to be used in animal cells, derived from E.coli transposons Tn9; it has also been used to a certain extent in plants.

3. The CAT gene confers antibiotic resistance.
A. True
B. False
Answer: A
Clarification: CAT gene encodes the enzyme chloramphenicol acetyltransferase, which confers resistance to antibiotic chloramphenicol.

4. Simian Virus 40 (SV40) is an example of ____________
A. Caulimovirus
B. Polyomavirus
A. Plant virus
D. Retrovirus
Answer: B
Clarification: Transient transformation can be achieved using replicon vectors that contain origins of replication derived from certain viruses of the polyomavirus family such as SV40.

5. Polyomavirus vectors such as SV40 are used especially for ____________
A. Gene expression
B. Gene manipulation
A. Recombinant proteins
D. Hybrid vector production
Answer: C
Clarification: These viruses cause lytic infections, during the infection cycle viral gene products accumulate at high levels. Hence this strategy is used to produce recombinant proteins.

6. Which is the first virus to be developed as an animal vector?
A. Papillomavirus
B. SV40
A. Adenovirus
D. HIV
Answer: B
Clarification: SV40 was the first animal virus to be characterized in detail at the molecular level and for this reason, it was also the first to be developed as a vector.

7. What is the approximate size of the SV40 vector?
A. 1 kb
B. 3 kb
A. 5 kb
D. 7 kb
Answer: C
Clarification: Simian Virus 40 (SV40) has a small icosahedral capsid and a circular double-stranded DNA genome of approximately 5 kb. It contains the early genes and the late genes.

8. Transcription in SV40 is controlled by ___________
A. Regulatory element
B. Late genes
A. Early genes
D. Promoter
Answer: A
Clarification: Transcription in SV40 is controlled by a complex regulatory element located between the early and late regions, and this includes early and late promoters, an enhancer and the origin of replication.

9. How many proteins are produced during the first stage of SV40 infection cycle?
A. 1
B. 2
A. 3
D. 4
Answer: B
Clarification: During the first stage of SV40 infection cycle, the early transcript produces two proteins, known as large T and small t tumor antigens.

10. What is the function of the T-antigen of SV40 viral vectors?
A. Genome replication
B. Translation
A. Transcription
D. Conjugation
Answer: A
Clarification: The function of T-antigen is particularly important as this protein binds to the viral origin of replication and is absolutely required for genome replication.

11. What function does an “oncoprotein” serve?
A. Controlled cell proliferation
B. Ceased cell proliferation
A. Uncontrolled cell proliferation
D. Initiates cell proliferation
Answer: C
Clarification: The T-antigen also acts as an oncoprotein, working with the host cell’s cycle machinery and causing uncontrolled cell proliferation.

12. Which type of infection is caused by the human BK virus?
A. Viral
B. Lytic
A. Latent
D. Carcinogenic
Answer: C
Clarification: Human BK virus causes latent infections in which the viral genome is maintained as a low to moderate copy-number replicon that does not interfere with host cell growth.

13. An epstein-barr virus causes a latent infection.
A. True
B. False
Answer: A
Clarification: Epstein-Barr virus causes latent infections in which the viral genome is maintained as a low to moderate copy-number replicon that does not interfere with host cell growth.

14. What are polyadenylation signals?
A. Inducers
B. Terminators
A. Promoters
D. Replicons
Answer: B
Clarification: Polyadenylation signals are terminators required in eukaryotic genes to generate a defined 3’ end to the mRNA.

15. Which of the following is a source of Poly(A. sites, incorporated into mammalian vectors?
A. Mouse beta-globin
B. Bovine serum albumin
A. Maltose binding protein
D. Agrobacterium
Answer: A
Clarification: Poly-adenyl sites from the Simian 40 Virus early transcription unit or mouse beta-globin gene are often incorporated into mammalian expression vectors.

To practice all exam questions on Vector Biology, .