Category: Vector Biology Objective Questions

Tricky Vector Biology Questions and Answers focuses on “Vectors for Mammals – 13”.

1. What is the reason for a large genome of poxyvirus?
A. Encodes for all human genes
B. Encodes for replication machinery
A. Encodes all promoters
D. Contains a large portion of junk DNA
Answer: B
Clarification: The large genome and structural complexity of the virus is because it must encode and package all its own DNA replication and transcription machinery.

2. Why are recombinant genomes of poxyvirus non-infectious?
A. Virus packages its own DNA
B. Host packages viral DNA
A. DNA remains unpacked
D. Virus packages unpacked
Answer: A
Clarification: Since the virus normally packages its own replication and transcription enzymes, recombinant genomes introduced into cells by transfection are generally non-infectious.

3. 5-bromodeoxyuridine is an analog of ___________
A. Pyrimidine
B. Alanine
A. Valine
D. Thymidine
Answer: D
Clarification: In one selection regime strategy, the transgene is inserted into the viral TK gene and negative selection using the thymidine analog 5-bromodeoxyuridine.

4. When transgene is inserted into the viral hemagglutinin locus, wild-type plaques turn ________
A. Red
B. White
A. Blue
D. Clear
Answer: A
Clarification: When transgene is inserted into the viral hemagglutinin locus, if chicken erythrocytes are added to the plate of infected cells, wild-type plaques turn red and recombinants turn clear.

5. NEO is a type of ____________
A. Selectable marker
B. Screenable marker
A. Promoter
D. Inducer
Answer: A
Clarification: Since vaccinia vectors have a high capacity for foreign DNA, selectable markers such as NEO can be co-introduced with the experimental transgene to identify recombinants.

6. LacZ’ is a screenable marker used with Vaccinia vectors.
A. True
B. False
Answer: A
Clarification: Since vaccinia vectors have a high capacity for foreign DNA, screenable markers such as LacZ’ can be co-introduced with the experimental transgene to identify recombinants.

7. Transgene expression in vaccinia vectors depends on ___________
A. Exogenous promoter
B. Endogenous promoter
A. Endogenous inducer
D. Exogenous inducer
Answer: B
Clarification: Transgene expression usually needs to be driven by an endogenous vaccinia promoter, since transcription relies on proteins supplied by the virus.

8. Highest expression levels in Vaccinia vectors are produced by ______ promoters.
A. P11
B. P7.5
A. 4b
D. P10
Answer: A
Clarification: The highest expression levels are provided by late promoters such as P11, allowing the production of up to 1 microgram of protein.

9. Vaccinia vectors cannot be used to express genes with __________
A. Exons
B. Junk DNA
A. Viral components
D. Introns
Answer: D
Clarification: Since the cytoplasm lacks not only host transcription factors but also the nuclear splicing apparatus, vaccinia vectors cannot be used to express genes with introns.

10. Which of the following sequence must be removed from DNA expressed in Vaccinia vectors?
A. TTTTTNT
B. TTTTTTT
A. NNNNNNN
D. TNTNTNT
Answer: A
Clarification: The sequence TTTTTNT must be removed from all foreign DNA sequences expressed in Vaccinia vectors since the virus uses this as a transcriptional terminator.

11. A useful binary expression system contains Vaccinia virus and bacteriophage ________
A. T7
B. T5
A. T8
D. T9
Answer: A
Clarification: A useful binary expression system has been developed, in which the transgene is driven by the bacteriophage T7 promoter and the T7 polymerase.

12. The vaccinia virus cannot be used to express antigens from other infectious agents.
A. True
B. False
Answer: B
Clarification: The vaccinia virus cannot be used to express antigens from other infectious agents by replacing the Vaccinia Tk locus with transgene encoding hepatitis B surface antigen.

13. Which cells were transfected in an early demonstration that vaccinia virus could be used to express antigens from other infectious agents?
A. Human cells
B. Insect cells
A. Plant cells
D. Monkey cells
Answer: D
Clarification: The transgene is cloned in a plasmid and this plasmid is then transfected into vaccinia-infected monkey cells, and recombinant vectors are then selected.

14. Vaccinia viruses expressing the influenza hemagglutinin gene were used to immunize ____________
A. Hamsters
B. Humans
A. Rabbits
D. Cow
Answer: A
Clarification: Vaccinia viruses expressing the influenza hemagglutinin gene are used to immunize hamsters, and induce resistance to influenza.

15. Resistance to SIV and HIV-2 was shown by infecting _______ with Vaccinia vectors.
A. Cow
B. Plants
A. Drosophila
D. Mouse
Answer: D
Clarification: Monkeys infected with recombinant vaccinia and canarypox vectors have shown resistance SIV and HIV-2.

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Vector Biology Multiple Choice Questions on “Vectors for Plants – 1”.

1. When were the cloning vectors for plants developed?
A. 1900
B. 1980
A. 2000
D. 1910
Answer: B
Clarification: The cloning vectors for plants were first developed in the 1980s and their use has led to the genetically modified crops.

2. Vectors based on naturally occurring ____________ of Agrobacterium are used in plants.
A. Plasmids
B. Phages
A. Cos sites
D. Chromosome
Answer: A
Clarification: Three types of vector systems with varying degrees of success are used in plants. One of them is vectors based on naturally occurring plasmids of Agrobacterium.

3. What is Agrobacterium tumefaciens?
A. Plant species
B. Plant virus
A. Soil microorganism
D. Fertilizer
Answer: C
Clarification: Agrobacterium tumefaciens is a soil micro-organism that causes crown gall disease in many species of dicotyledonous plants.

4. Which disease is caused by Agrobacterium tumefaciens?
A. Crown gall
B. Carcinoma
A. Angiogenesis
D. Fungal infection
Answer: A
Clarification: Crown gall occurs when a wound on the stem allows A. Tumefaciens bacteria to invade the plant. After the infection bacteria causes a cancerous proliferation of the stem tissue in the region of the crown.

5. The ability to cause crown gall disease is associated with the presence of __________ within the bacterial cell.
A. Plasmid
B. Origin
A. Replication sites
D. Polymerase
Answer: A
Clarification: The tumor inducing plasmid present in the bacterial cell of agrobacterium tumefaciens is responsible for causing the crown gall disease.

6. What is the size of the Ti plasmid?
A. 10 kb
B. 100 kb
A. 20 kb
D. 200 kb
Answer: D
Clarification: The Ti plasmid is a large plasmid of 200 kb size or greater. It carries numerous genes involved in the infective process.

7. A remarkable feature of the Ti plasmid is that after infection a part of the molecule is integrated into plant chromosomal DNA.
A. True
B. False
Answer: A
Clarification: The part of the Ti plasmid that gets integrated into the plant chromosome after infection is called the T-DNA or the transfer DNA.

8. What is the size range of T-DNA?
A. 15 and 30 kb
B. 5 and 10 kb
A. 50 and 100 kb
D. 1 and 5 kb
Answer: A
Clarification: The size range of T-DNA is between 15 and 30 kb depending upon the strain of bacteria. The whole of this region is integrated into a host chromosome.

9. The T-DNA is maintained in ______ form in the plant.
A. Stable
B. Unstable
A. Integrated
D. Loosely bound
Answer: A
Clarification: The T-DNA after infection and transfer to the host chromosome remains in the plant in a stable form and is passed to the daughter cells after each cell division.

10. What is the special feature of T-DNA?
A. Expression of unusual genes
B. Repression of unusual genes
A. Cell proliferation
D. Cell death
Answer: A
Clarification: The T-DNA contains eight or so genes that are expressed in the plant cell and are responsible for cancerous properties of the transformed cells.

11. What are the plant host cells that contain T-DNA called?
A. Infected
B. Attacked
A. Transformed
D. Transfected
Answer: C
Clarification: When the T-DNA from Ti plasmid present inside the bacterial cell Agrobacterium tumefaciens is transferred to the chromosome of the plant host, the host cells are called transformed.

12. What are opines?
A. Bacterial nutrients
B. Plant nutrients
A. Telomere sites
D. T-DNA ends
Answer: A
Clarification: The genes present on the T-DNA fragment direct the synthesis of unusual compounds called opines, that the bacteria use as nutrients.

13. What is the binary vector strategy used for?
A. Vector insertion into host
B. Insertion of new DNA
A. Manipulation of vector
D. Manipulation of host
Answer: B
Clarification: Due to the big size of Ti plasmid it is extremely difficult to find a unique restriction site. Novel strategies are hence used for the insertion of foreign DNA in the plasmid.

14. What is the basis of “binary vector” strategy?
A. No physical attachment
B. Big size
A. Strain dependence
D. Lysogenic/lytic cycle
Answer: A
Clarification: The binary vector strategy is based on the observation that the T-DNA does not need to be physically present/attached to the rest of the Ti plasmid.

15. In the binary vector strategy, the sizes of the two vectors used are _____ for bigger plasmid and ______ for smaller T-DNA plasmid.
A. 200, 20
B. 170, 20
A. 200, 50
D. 170, 50
Answer: B
Clarification: There are two vectors in the binary vector system. The bigger one is 170 kb in size and a smaller plasmid containing only the T-DNA region is 20 kb in size.

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Vector Biology Multiple Choice Questions on “Bacteriophages – 1”.

1. Which of the following is not true for a bacteriophage?
A. A very simple structure
B. Consist either DNA or RNA
A. Bacteriophages are viruses
D. Complex structure that infects bacteria
Answer: D
Clarification: Bacteriophages are viruses that specifically infect bacteria but these are very simple structures consisting merely of a DNA/RNA molecule surrounded by a protective coat.

2. What is the capsid (protective coat) of the bacteriophage made up of?
A. DNA
B. RNA
A. Protein
D. Organic acids
Answer: C
Clarification: The protective coat or capsid is made up of protein molecules which surround the nucleic acid molecule carrying a number of genes including several for the replication of phage.

3. Which of the following is an example of head-and-tail bacteriophage?
A. M13
B. Lambda phage
A. Pbr322
D. M16
Answer: B
Clarification: Enterobacteria phage (Lambda phage) infects the bacterial species E.Coli. It consists of an icosahedral head, measuring 50-60 nanometers in diameter and a flexible tail that is around 150 nanometers in length.

4. The replication of phage DNA molecule is associated with which step in the infection cycle of a bacteriophage?
A. First step
B. Second step
A. Third step
D. Preparation stage
Answer: B
Clarification: The general pattern of infection, which is the same for all the phages is a three step process. The first step is the attachment of phage to the surface of bacterium and subsequent injection of its DNA into the cell, second step is replication of the injected DNA.

5. The cycle which is completed quickly in the infection by a phage is ________
A. Lysogenic
B. Lytic
A. Replication
D. Capsid formation
Answer: B
Clarification: With some phage types the entire infection cycle is completed very quickly, possibly in less than 20 minutes. This type of rapid infection is called a lytic cycle, as a release of the new phage particles is associated with lysis of the bacterial cell.

6. Which is a reason of instability of phage DNA molecule in the host cell in a lytic cycle?
A. The huge size of phage DNA
B. Inability of replicative enzymes
A. Immediate synthesis of capsid
D. Lytic cycle inefficiency
Answer: C
Clarification: The characteristic feature of a lytic infection cycle is that phage DNA replication is immediately followed by synthesis of capsid proteins and the phage DNA molecule is never maintained in a stable condition in the host cell.

7. Which infection cycle is characterized by retention of the phage DNA molecule in the host bacterium for many thousands of cell division?
A. Lysogenic cycle
B. Lytic cycle
A. Integrative Phase
D. Protein synthesis
Answer: A
Clarification: With many lysogenic phages the phage DNA is inserted into the bacterial genome in a manner similar to episomal insertion. The integrated form of the phage DNA is called the prophage and bacterium is referred to as a lysogen.

8. Which of the following statements is not true in the context of infection by an M13 phage?
A. Lytic phage
B. Lysogenic phage
A. New phage particles are continually synthesized
D. The DNA is not integrated in host genome
Answer: A
Clarification: M13 is a lysogenic phage that follows a different infection cycle when M13 infects a bacterium, new phage particles are assembled and released continually from the cell. There is no integration of phage DNA into the bacterial chromosome and lysis of the cell also never occurs.

9. Approximate size of lambda phage is _______
A. 23 kb
B. 100 kb
A. 49 kb
D. 12 kb
Answer: C
Clarification: Lambda phage is extensively used as a cloning vector. The lambda DNA molecule is 49 kb in size and has been intensively studied by the techniques of gene mapping and DNA sequencing.

10. What are sticky ends?
A. Ends of M13 vector
B. 12 nucleotide stretch in lambda phage
A. The replicated product phage DNA
D. Ends on two sides of origin
Answer: B
Clarification: At either end of the lambda DNA molecule is a short 12 nucleotide stretch in which the DNA is single stranded. The two single strands are complementary and base pair with each other to form a circular completely double stranded molecule.

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Gene Manipulation Multiple Choice Questions & Answers focuses on “Gene Manipulation in Fish”.

1. Gene transfer to fish is generally carried out using ____________
A. YAC vectors
B. Electroporation
A. Microinjection
D. Ultracentrifugation
Answer: C
Clarification: Gene transfer to fish is generally carried out by microinjection, but other methods are emerging. Fish transgenesis can be used to study gene function.

2. Zebrafish can be used to study gene function.
A. True
B. False
Answer: A
Clarification: Fish transgenesis can be used to study gene function and regulation, e.g. in model species such as the zebrafish and medaka.

3. Salmon and trout are ___________
A. Hybrids
B. Commercially important
A. Protein producers
D. Transgenic fish
Answer: B
Clarification: Model species such as Danio rerio and Oryzias latipes are used to improve the traits of commercially important species such as salmon and trout.

4. Gene transfer technology in fish has lagged behind that in _________
A. Bacteria
B. Virus
A. Mammals
D. Plants
Answer: C
Clarification: Gene transfer technology in fish has lagged behind that in mammals predominantly due to lack of suitable regulatory elements to control transgene expression.

5. The first transgenic fish carried transgenes driven by _________
A. Mammals
B. Xenopus
A. Virus
D. Bacteria
Answer: A
Clarification: The first transgenic fish carried transgenes driven by mammalian or viral regulatory elements and their performance varied considerably.

6. Attempts to express growth hormones were initially done with ____________
A. Salmon
B. Xenopus
A. Octopus
D. Trout
Answer: D
Clarification: Attempts to express growth hormone genes in trout initially met with little success and this may have been due to the inability of fish cells to process mammalian introns correctly.

7. Fish are advantageous assay systems because of their ____________
A. Size
B. Fecundity
A. Nutritional requirements
D. Environment
Answer: B
Clarification: Fish are advantageous assay systems because of their fecundity and the fact that fertilization and development are external and the ease with which embryos can be produced.

8. How many kinds of embryos can be produced using fish for the purpose of transgenesis?
A. 1
B. 2
A. 3
D. 4
Answer: B
Clarification: The fertilization and development in fish are external and the ease with which haploid and uniparental diploid embryos can be produced.

9. Fish, like frogs can be used for __________ assays.
A. Integrative
B. Nonfunctional
A. Transient
D. Permanent
Answer: C
Clarification: Like frogs, the injection of DNA into fish eggs and early embryos leads to extensive replication and expression from unintegrated transgenes and hence they can be used for transient assays.

10. Transgenic fish lines are created by ___________ of DNA into the genome.
A. Excision
B. Partial attachment
A. Inactivation
D. Integration
Answer: D
Clarification: Some of the DNA integrates into the genome leading to germline transformation and the production of transgenic fish lines.

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Gene Manipulation Questions and Answers for Freshers focuses on “Basic Laboratory Techniques – 2”.

1. The technique of sucrose gradients was later superseded by __________
A. Electroporation
B. Electrodialysis
A. Gel electrophoresis
D. Biolistics
Answer: C
Clarification: The first experiments of cutting and joining DNA were monitored by velocity sedimentation in sucrose gradient; this has been entirely superseded by gel electrophoresis.

2. Gel electrophoresis is not used as a purification technique.
A. True
B. False
Answer: B
Clarification: Gel electrophoresis is not only used as an analytical method, but it is also routinely used preparatively for the purification of DNA.

3. Polyacrylamide in Gel electrophoresis technique is preferred for _______________
A. Smaller DNA
B. Bigger chunks
A. Proteins
D. Sucrose
Answer: A
Clarification: Agarose is convenient for separating DNA fragments ranging a few hundred base pairs in size and polyacrylamide is preferred for smaller DNA fragments.

4. The average pore size of an agarose gel depends on _______________
A. Casting tray
B. Buffer composition
A. Amount
D. Protein
Answer: B
Clarification: An agarose gel is a complex network of polymeric molecules whose average pore size depends on the buffer composition.

5. DNA molecules in an electrophoresis gel exhibit which behavior?
A. Black body
B. Inelastic
A. Elastic
D. Reputation
Answer: C
Clarification: DNA molecules display elastic behavior by stretching in the direction of the applied field and then contracting into dense balls.

6. Molecules greater than what size cannot be separated without using electric field?
A. 1 kb
B. 2 kb
A. 10 kb
D. 20 kb
Answer: D
Clarification: With molecules about 20 kb in size, it is difficult to separate molecules without recourse to pulsed electric fields.

7. PFGE was developed in which year?
A. 1970
B. 1984
A. 1950
D. 1944
Answer: B
Clarification: In pulsed-field gel electrophoresis (PFGE), developed by Schwartz and Cantor 1984, molecules as large as 10 Mb can be separated in agarose gels.

8. In PFGE, the direction of DNA molecules is periodically ________
A. Hindered
B. Changed
A. Paused
D. Slowed
Answer: B
Clarification: The DNA is caused to periodically alter its direction of migration by regular changes in the orientation of electric field with respect to the gel.

9. Reorientation angle is difference between ____________
A. Migration direction
B. Field direction
A. Tray direction
D. Gel direction
Answer: A
Clarification: The difference between the directions of migration induced by each of the electric fields is the reorientation angle and corresponds to the angle that the DNA must turn as it changes its direction of migration each time the fields are switched.

10. Reorientation angle is the angle of ______________
A. DNA
B. Protein
A. Vector
D. Gel
Answer: A
Clarification: The reorientation angle corresponds to the angle that the DNA must turn as it changes its direction of migration each time the fields are switched.

11. Samples do not run in straight lines is a ________ of PFGE.
A. Advantage
B. Disadvantage
A. Cost efficiency
D. Ease
Answer: B
Clarification: A major disadvantage of PFGE is that the samples do not run in straight lines, which makes the subsequent analysis of samples difficult.

12. CHEF is a type of _____________
A. Vector
B. Gel
A. Electrophoresis
D. Gene
Answer: C
Clarification: The contour-clamped-homogeneous electric field electrophoresis (CHEF) solves the problems encountered in PFGE.

13. The reorientation angle used for yeast in CHEF is _____
A. 106⁰
B. 110⁰
A. 120⁰
D. 200⁰
Answer: A
Clarification: The reorientation angle can be varied in newer CHEF systems and it has been found that for whole yeast chromosomes the migration rate is fastest at 106⁰.

14. DNA fragments of several ________ can be handled using CHEF.
A. Tens
B. Hundreds
A. Thousands
D. Mixed
Answer: B
Clarification: DNA as large as 200-300 kb are routinely handled in genomics work and these can be separated in a matter of hours using CHEF.

15. Which reorientation angle is most suited in CHEF for DNA up to several hundred base pairs?
A. 100⁰
B. 90⁰
A. 200⁰
D. 300⁰
Answer: B
Clarification: DNA as large as 200-300 kb are routinely handled in genomics work and these can be separated in a matter of hours using CHEF.

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Vector Biology written test Questions & Answers focuses on “Vectors for Mammals – 12”.

1. What does the replicase protein of alphaviral vectors produce?
A. Transgene
B. Complementary strand
A. Daughter genome
D. Host genome
Answer: B
Clarification: 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.
A. True
B. False
Answer: B
Clarification: 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 __________
A. Promoter
B. Subgenomic promoter
A. Inducer
D. Double promoter
Answer: B
Clarification: 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 _________________
A. RNAs
B. Proteins
A. DNA
D. Transgene
Answer: A
Clarification: 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 __________
A. Promoter
B. Inducer
A. RNA
D. Transgene
Answer: D
Clarification: 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
A. Transgene
D. Genomic size
Answer: A
Clarification: 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
A. Expression as a fusion protein
D. To decrease expression
Answer: C
Clarification: 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
B. Hybrid
A. Alphavirus
D. Baculovirus
Answer: A
Clarification: 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?
A. SP2
B. SP4
A. SP6
D. SP8
Answer: C
Clarification: 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?
A. Circularization
B. Linearization
A. DNA replication
D. Transfection
Answer: B
Clarification: 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?
A. SV10
B. SV20
A. SV30
D. SV40
Answer: D
Clarification: 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.
A. True
B. False
Answer: A
Clarification: 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 ___________
A. Poxvirus
B. Hybrid vector
A. Alphavirus
D. Vaccination
Answer: A
Clarification: 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
A. Expression mechanism
D. Replication site
Answer: D
Clarification: 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
A. 300 kb
D. 10 kb
Answer: C
Clarification: The poxviruses have a complex structure and a large double-stranded linear DNA genome. The virus packages and encodes its DNA all by itself.

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