Category: Vector Biology Objective Questions

Vector Biology Multiple Choice Questions on “Cloning Vectors for E.Coli – 1”.

1. Which organism has the highest number of vectors?
A. Yeast
B. Mammalian cells
A. E.coli
D. Fungi
Answer: C
Clarification: E.coli owing to simplicity and the ease of culturing and manipulation has played a central role in research for a few decades.

2. Which is an example of a simplest vector (in terms of size)?
A. 2 micron circle
B. Bacteriophage
A. Plasmid
D. YAC
Answer: C
Clarification: The simplest and most widely used vectors are plasmids. These are naturally present in certain species of bacteria usually imparting some unusual characteristic to the host.

3. Bolivar and Rodriguez constructed which vector?
A. Yip7
B. R6-5
A. pUC8
D. Pbr322
Answer: D
Clarification: One of the vectors developed was Pbr322 although no longer used extensively in research as for now but it still illustrates some of the fundamental properties of any plasmid cloning vector.

4. Which of the following properties is not taken into account while looking for a suitable vector?
A. Size
B. Parent organism
A. Restriction site
D. Origin of replication
Answer: B
Clarification: Parent organism gives no estimate of how the vector gets inserted into the host cell and how efficient it is in carrying the foreign DNA.

5. Which antibiotic resistance is present in pBR322?
A. Ampicillin
B. Kanamycin
A. Lactase
D. Gentamycin
Answer: A
Clarification: There are genes incorporated in the pBR322 molecule that code for the enzyme beta-lactamase which detoxifies ampicillin that may be present in the host environment.

6. Size of Pbr322 is _______
A. 100 kb
B. 10 kb
A. 4.3 kb
D. 1 kb
Answer: B
Clarification: Pbr322 is 4363 bp in size, which means that not only can it be purified with ease, but so can recombinant molecules be constructed with it.

7. How many sets of antibiotic resistance does the plasmid Pbr322 carry?
A. 1
B. 3
A. 2
D. 4
Answer: C
Clarification: The plasmid contains two sets of antibiotic resistance genes on coding for the ampicillin resistance and the other for tetracycline resistance.

8. pBR327 is a conjugative plasmid.
A. True
B. False
Answer: B
Clarification: Pbr327 is a modification of the plasmid Pbr322 and during this modification, the conjugative abilities were destroyed, this is important in biological containment.

9. Which selection system is used in the Puc8 plasmid?
A. Antibiotic selection
B. Lactose selection
A. Auxotrophic mutant selection
D. Plaque morphology selection
Answer: B
Clarification: The identification of recombinants produced by Puc8 plasmid is done by insertional inactivation of lacz’ gene, distinction is done on the basis of the observed colour of the colonies (blue or white).

10. What is the copy number of the pUC8 plasmid vector?
A. 5-10
B. 50-100
A. 100-200
D. 500-700
Answer: D
Clarification: The high copy number of the plasmid; higher than the previous members of pBR pedigree, was attributed to a chance mutation.

11. What additional feature does Pgem3Z has which makes it a suitable vector for in vitro transcription of cloned genes?
A. Unique Ori
B. Promoters
A. Clustered cloning sites
D. LacZ’ gene
Answer: B
Clarification: Pgem3Z has two promoters namely: T7 promoter and SP6 promoter; both being specific for the RNA Polymerase that is encoded by bacteriophage T7 and SP6.

12. The size of M13 phage vector is _________
A. 3 kb
B. 6.4 kb
A. 15.4 kb
D. 20.4 kb
Answer: B
Clarification: The genomic size of M13 bacteriophage is 6.4 kb which is bigger than most of the plasmid cloning vectors. Most of this length of M13 is taken up by ten closely placed genes.

13. There is a sequence region in M13 where the foreign DNA can be inserted. What is this sequence called?
A. Inverted repeat
B. Palindromic
A. Intergenic
D. Interstitial
Answer: C
Clarification: The intergenic sequence in M13 is 507 nucleotides long and is flanked by the genes IV and II. There are a total of 10 closely placed genes and this intergenic sequence.

14. The M13mp1 contains __________
A. LacZ’ gene
B. Ampicillin Resistance gene
A. Restriction sites
D. Tetracycline resistance gene
Answer: A
Clarification: The M13mp1 vector is constructed by incorporating LacZ’ gene in the intergenic sequence. This lacZ’ gene however does not harbor any restriction endonuclease site.

15. The M13mp2 consists ________ restriction site.
A. BamHI
B. AluI
A. PvuII
D. EcoRI
Answer: D
Clarification: This vector is a modification of M13mp1 and contains a unique restriction endonuclease site resulting from a mutation of GGATCC to GAATCC.

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Gene Manipulation Multiple Choice Questions on “Large Scale Mutagenesis and Interference”.

1. Mutations can be introduced by ____________
A. Cloning
B. Recombination
A. Ligation
D. Gene targeting
Answer: D
Clarification: Mutations can be introduced into predefined genes in vivo through a process termed as gene targeting which involves homologous recombination.

2. Gene-knockout is the generation of a null-gene.
A. True
B. False
Answer: A
Clarification: When the aim is to inactivate the target gene completely and generate a null allele, the term gene knockout is often used.

3. Embryonic stem cells are __________
A. Totipotent
B. Pluripotent
A. Dead
D. Multipotent
Answer: B
Clarification: Embryonic stem cells can be cultured like any established cell line, but they are derived from the very early mouse embryo and are therefore pluripotent.

4. The only organism in which systematic gene targeting has been achieved is ____________
A. Mouse
B. Drosophila
A. Fish
D. Yeast
Answer: D
Clarification: The only organism in which systematic gene targeting has been achieved is the yeast Saccharomyces Cerevisiae. Its genome contains about 6000 open reading frames.

5. The EUROFAN project involves the use of _________ generated cassettes.
A. PCR
B. Ultracentrifugation
A. Electroporation
D. Cloning
Answer: A
Clarification: The EUROFAN project involves the use of PCR-generated cassettes in which a selectable marker is placed between 50 basepair elements.

6. Genome-wide random mutagenesis is applicable to _________
A. Fish
B. Mammals
A. All organisms
D. Bacteria
Answer: C
Clarification: Saturation mutagenesis has been used for many years to identify mutations affecting specific crucial biological processes.

7. Insertional mutagenesis facilitates __________
A. Cloning
B. PCR
A. Recombination
D. Centrifugation
Answer: C
Clarification: Insertional mutagenesis leaves a DNA tag in the interrupted gene, which facilitates cloning and gene identification. It is the most popular mutagenesis strategy.

8. Ribozymes are _________ molecules.
A. Toxic
B. Large
A. DNA
D. Catalytic
Answer: D
Clarification: Ribozymes are catalytic molecules that destroy targeted MRNAs. They carry out site-specific cleavage and ligation reactions.

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Gene Manipulation Multiple Choice Questions on “Genomic and cDNA Libraries”.

1. The first genomic libraries were cloned in _______________
A. Plasmid
B. Bacteria
A. Human
D. Plants
Answer: A
Clarification: Genomic DNA libraries are generated by fragmenting the genome and cloning overlapping fragments in vectors. The first libraries were cloned in simple plasmids and phage vectors.

2. Genomic library construction is concerned with ___________
A. Gene isolation
B. Protein production
A. Antibiotics
D. Regeneration
Answer: A
Clarification: Genomic libraries are useful to examine how we can study and isolate a given gene; the basic principles apply to all genomes.

3. Which DNA is restricted to making a genomic library?
A. Genomic
B. Plasmid
A. Phage
D. Plant
Answer: A
Clarification: Total genomic DNA of an organism is digested using restriction endonuclease and the fragments are inserted into a suitable phage.

4. What is the approximate size of fragments given off by EcoR1?
A. 1 kb
B. 2 kb
A. 3 kb
D. 4 kb
Answer: D
Clarification: EcoR1 is a restriction endonuclease; that is it cleaves the DNA within the double helical structure and gives off the fragments of approximately 4 kb in size.

5. A genomic library is a collection of _____________
A. Genes
B. Proteins
A. Vectors
D. Recombinants
Answer: D
Clarification: A very large number of recombinants are produced by restricting with endonucleases and then inserting them into suitable vectors, to make up a genomic library.

6. If a gene is large, it may be cut more than once by an endonuclease.
A. True
B. False
Answer: A
Clarification: If a gene is large then it can harbor many recognition sites for an endonuclease and therefore it may be cleaved more than once.

7. The Clarke and Carbon formula relates the ____________ of including a DNA fragment in a random library.
A. Probability
B. Effects
A. Temperature change
D. Vector requirement
Answer: A
Clarification: The Clarke and Carbon formula, developed in 1976 relates the probability of including any DNA sequence in a random library of N independent recombinants.

8. In the strategy devised by Maniatis, how many restriction enzymes were used?
A. 1
B. 2
A. 3
D. 4
Answer: B
Clarification: In order to control the size of digested fragments that eventually are inserted in vectors, two restriction enzymes were used by Maniatis.

9. The restriction enzymes used by Maniatis had recognition site of ____ nucleotides.
A. 1
B. 2
A. 3
D. 4
Answer: D
Clarification: The restriction endonucleases used in the strategy developed by Maniatis in 1978; had tetranucleotide restriction site.

10. Which kind of packing is done for the fragmented genes?
A. In vivo
B. Population
A. Group
D. In vitro
Answer: D
Clarification: In vitro packaging ensures that appropriately large number of independent recombinants can be recovered. Packaging is done by inserting the genes into the vectors.

11. HaeIII and AluI have ___________ recognition sites.
A. Different
B. Similar
A. Short
D. Unrecognizable
Answer: A
Clarification: HaeIII and AluI are restriction endonucleases and have completely different recognition sites which generate random DNA fragments.

12. Linkers are required when using enzymes HaeIII and AluI.
A. True
B. False
Answer: A
Clarification: Both these enzymes have completely different recognition sites and hence produce randomly fragmented genes. Blunt ends are produced and linkers are required.

13. The ‘Charon series’ belongs to series of ____________
A. Genes
B. Vectors
A. Hosts
D. Enzymes
Answer: B
Clarification: The Charon series was developed by Blattner and Williams in 1979 and included insertional vectors and replacement vectors.

14. Sau3AI is a _______ restriction endonuclease.
A. Single
B. Double
A. Hybrid
D. Weak
Answer: A
Clarification: Sau3AI is a single restriction endonuclease that cuts frequently and allows for a convenient simplification for the generation of genes.

15. Lambda EMBL3 is a ____________
A. Gene
B. Phage
A. Phage Vector
D. Protein
Answer: C
Clarification: Lambda EMBL3 is a replacement vector. Fragments digested with Sau3AI which is a single restriction enzyme can be readily inserted into this vector.

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Vector Biology Multiple Choice Questions on “Single Stranded DNA Vectors Cloning – 1”.

1. Which of the following is not a filamentous coliphage vector?
A. M13
B. Lambda
A. F1
D. Fd
Answer: B
Clarification: M13, F1, FD are filamentous coliphages containing a circular single-stranded DNA molecule. These have been developed as vectors because of various advantages.

2. Coliphages are single-stranded vectors.
A. True
B. False
Answer: A
Clarification: M13, F1, FD are filamentous coliphages containing a circular single-stranded DNA molecule. These have been developed as vectors because of various advantages.

3. What is the average size of single-stranded vector?
A. 6400 nucleotides
B. 1200 nucleotides
A. 2500 nucleotides
D. 5500 nucleotides
Answer: A
Clarification: The phage particles have dimensions 900*9 nm and contain a single-stranded circular DNA molecule, which is 6407 (M13) or 6408 (fD).

4. The complete nucleotide sequences of fD and M13 are ___ percent identical.
A. 25
B. 97
A. 40
D. 65
Answer: B
Clarification: The complete nucleotide sequences of fd and M13 are available and they are 97 percent identical. The difference is mainly in isolated nucleotides.

5. The filamentous single-stranded phages infect only _________________
A. Fungi
B. Mammals
A. Plants
D. Enteric bacteria
Answer: D
Clarification: The filamentous phages only infect strains of enteric bacteria harboring F pili. The adsorption site appears to be the end of the F pilus.

6. How many phage particles are released per generation upon coliphage infection?
A. 10
B. 100
A. 500
D. 1000
Answer: D
Clarification: Replication of phage DNA does not result in host lysis. Infected cells grow albeit at a slower rate. Around 1000 phage particles may be released into the medium.

7. Phage DNA enters the cell by a process in which ________ and replication are tightly coupled.
A. Encapsulation
B. Decapsidation
A. Translation
D. Transcription
Answer: B
Clarification: The single stranded phage DNA enters the cell by a process in which decapsidation and replication are tightly coupled. Conversion to RF takes place.

8. What is RF?
A. Plasmid
B. Coliphage
A. Replicative form
D. Hybrid vector
Answer: C
Clarification: The capsid proteins enter the cytoplasmic membrane as the viral DNA passes into the cell while being converted to a double-stranded replicative form.

9. The RF multiplies ________
A. Slowly
B. Rapidly
A. Moderately
D. Does not multiply
Answer: B
Clarification: The capsid proteins enter the cytoplasmic membrane as the viral DNA passes into the cell while being converted to a double-stranded replicative form. RF replicates rapidly.

10. What happens following the morphogenesis of the cell?
A. Progeny strands release
B. DNA replication
A. Host lysis
D. Degradation
Answer: A
Clarification: The progeny single strands are synthesized and released from the cell as filamentous particles the following morphogenesis at the cell membrane.

11. Dominant selectable markers can be used with __________
A. Any cell type
B. Mutant cells
A. Wild-type cells
D. Recombinant cells
Answer: A
Clarification: Endogenous markers are largely superseded by so-called dominant selectable markers, which confer a phenotype that is entirely novel to the cell and can hence be used in any cell type.

12. What are dominant selectable markers?
A. Drug-resistance genes
B. Inducing genes
A. Exogenous genes
D. Endogenous genes
Answer: A
Clarification: The dominant selectable markers are usually drug-resistance genes of bacterial origin and transformed cell is selected on a medium that contains the drug at an appropriate concentration.

13. Methotrexate is an analog of __________
A. Aminopterin
B. Kanamycin
A. Folic acid
D. Gentamycin
Answer: C
Clarification: Methotrexate is a folic acid analog, which is a competitive inhibitor of the enzyme dihydrofolate reductase (DHFR).

14. With respect to mammalian cell cloning, salmon sperm DNA can serve as a source of ____________
A. Non-specific carrier
B. Specific carrier
A. Genomic DNA
D. Plasmid DNA
Answer: A
Clarification: Calcium phosphate transfection is mostly used and the specific donor DNA is often bulked with a non-specific carrier such as cleaved Salmon sperm.

15. One application in which the use of plasmid vectors is critical, in the case of mammals is ____________
A. Stable transformation
B. Transient transformation
A. Transfection
D. Transduction
Answer: B
Clarification: One application in which the use of plasmid vectors is critical, in the case of mammals is a transient transformation. Here the goal is to exploit the short-term persistence of extrachromosomal DNA.

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Vector Biology Multiple Choice Questions on “Vectors for Mammals – 2”.

1. What is the main use of shuttle vectors consisting of BPV and E.coli sequences?
A. Pharming
B. Gene therapy
A. Recombinant protein production
D. Recombinant DNA
Answer: C
Clarification: Shuttle vectors consisting of E.coli and BPV sequences are capable of replication in both mouse and bacterial cells and are hence used for recombinant protein production in mouse cell lines.

2. What is the similarity between AAV and Adenovirus?
A. Size
B. Host cell location
A. Host tissue location
D. Infection mechanism
Answer: C
Clarification: Adeno-associated virus which is unrelated to adenovirus but often found in the same infected tissues. AAV makes use of some proteins found in Adenovirus.

3. Which is the helper virus in an AAV?
A. Baculovirus
B. Adenovirus
A. Papillomavirus
D. Retrovirus
Answer: B
Clarification: AAV is found in the same infected tissues as Adenovirus because it makes use of some of the proteins synthesized by the adenovirus in order to complete its replication cycle.

4. Which of the following unusual property is associated with an Adeno-associated virus?
A. Always inserting at the same position
B. Always inserting at different position
A. Always falling short for integration
D. Jumping gene property
Answer: A
Clarification: In the absence of helper Adenovirus, the Adeno-associated virus genome inserts it into host’s DNA. With most integrative viruses this is a random event but AAV always inserts itself at the same position.

5. Which is the particular site of insertion of AAV?
A. Chromosome 4
B. Chromosome 5
A. Chromosome 9
D. Chromosome 19
Answer: D
Clarification: With most integrative viruses this is a random event but AAV always inserts itself at the same position, within human chromosome 19.

6. The most common use of Retroviruses is _________
A. Pharming
B. Gene therapy
A. Recombinant protein production
D. Molecular cloning
Answer: B
Clarification: Retroviruses are the most common vectors for gene therapy. Although they insert at random positions, the resulting integrants are very stable.

7. The resulting integrants of Retroviruses are unstable.
A. True
B. False
Answer: B
Clarification: Although they insert at random positions, the resulting integrants are very stable, which means that therapeutic effects of a cloned gene will persist for longer.

8. Microinjection is a process of transferring genes into _________ cells.
A. Mammalian
B. Plant
A. Yeast
D. Bacterial
Answer: A
Clarification: One of the reasons why viral vectors have not yet become widespread in mammalian gene cloning is because it was discovered in the early 1990s that the most effective way is microinjection.

9. Why is microinjection more satisfactory than using a viral vector for mammalian cells?
A. Compatibility
B. Ease of cloning
A. Avoiding infection and defects
D. Wide host range
Answer: C
Clarification: The procedure of microinjection is more satisfactory in that the use of a viral vector because it avoids the possibility that viral DNA will infect the cells and cause defects of one kind or the other.

10. What is a chimera mouse?
A. Comprising a mix of cloned and natural cells
B. Comprising a mix of cloned cells
A. Comprising only natural cells
D. Comprising tumorigenic cells
Answer: A
Clarification: After microinjection, the ES cells are placed in the embryo which is implanted into the foster mother. The resulting mouse is a chimera, which comprises a mixture of engineered and non-engineered cells.

11. A transgenic animal is the one that contains cloned genes in a few of its cells.
A. True
B. False
Answer: B
Clarification: Microinjection is the basis to create a transgenic animal, one that contains a cloned gene in all of its cells. A mouse is an example.

12. What are embryonic stem cells?
A. Pluripotent cells
B. Multipotent cells
A. Totipotent cells
D. Cells from transgenic mice
Answer: C
Clarification: Embryonic stem cells are obtained from within an early embryo and are totipotent, meaning that their developmental pattern is not present.

13. Non chimeric mice contain _________ in all their cells.
A. Totipotent cells
B. ES cells
A. Non-engineered cells
D. Cloned genes
Answer: D
Clarification: Non-chimeric mice, which contain the cloned gene in all their cells, are obtained by allowing the chimera to reproduce, as some of the offspring will be derived from egg cells that contain the cloned gene.

14. In transgenic animals, what is a foster mother?
A. From which ES cells are derived
B. From which embryo is derived
A. Into which embryo is implanted
D. Whose genes are used
Answer: C
Clarification: A transgenic mouse is generated by microinjection of a fertilized egg cell which is subsequently cultured in vitro for several cell divisions and then implanted into the foster mother.

15. Therapeutic effects of the cloned gene using which of the following vector will persist for longer?
A. Retrovirus
B. Baculovirus
A. Adenovirus
D. Papillomavirus
Answer: A
Clarification: Retroviruses are the most common vectors used for gene therapy and they produce very stable integrants in the host cells, hence their effects on cloned genes persist for longer.

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Vector Biology Multiple Choice Questions on “Identification of Recombinants”.

1. Which of the following refers to the inactivation of Insertional inactivation?
A. Host
B. Gene of Interest
C. Gene of the vector
D. Gene of the host
Answer: C
Clarification: The incorporation of a DNA fragment into the vector leads to inactivation of one more genes present on its genome and a characteristic coded by the inactivated gene will no longer be displayed by the host cells.

2. BamHI cuts the Pbr322 at just one position, within the cluster of genes that code for resistance to ___________
A. Tetracycline
B. Ampicillin
C. Kanamycin
D. Gentamycin
Answer: A
Clarification: Pbr322 carries genes that code for tetracycline resistance. When cleavage of the molecule is done using endonuclease to insert a DNA fragment, the tetracycline genes are deactivated and the resistance is lost.

3. On a medium containing ampicillin, when pBR322 recombinants were plated. Which of the following will not be able to grow?
A. pBR322 containing gene of interest
B. self-ligated Pbr22
C. non-transformants
D. transformed cells
Answer: C
Clarification: All transformed cells that are those which took up the plasmid will grow on the ampicillin plates because only tetracycline resistance gene is inactivated.

4. Which of the following techniques is used in recombinant identification?
A. Ligation
B. Isolation
C. Replica plating
D. Restriction digestion
Answer: C
Clarification: Recombinants are first plated onto an agar plate containing antibiotic, for further screening replica plating of previously grown colonies is done to check growth on second antibiotic containing plate.

5. lacZ’ gene present in a Puc series plasmid codes for which of the enzyme?
A. Beta-galactosidase
B. Lactase
C. Amylase
D. Nuclease
Answer: A
Clarification: lacZ’ gene codes for beta-galactosidase enzyme and cloning with a plasmid that contains this gene leads to insertional inactivation of the gene and recombinants are identified because of their inability to synthesize the enzyme.

6. Beta-galactosidase is one of a series of enzymes involved in the breakdown of lactose to glucose plus galactose. It is normally coded by the gene lacZ, which resides on the E.Coli chromosome.
A. True
B. False
Answer: A
Clarification: The lacZ gene is encoded by the E.coli genome but some strains have modified lacZ gene and they can only synthesize beta-galactosidase enzyme when they harbor a plasmid that contains the missing element of the gene.

7. In screening for Puc8 recombinants, which color colonies will be the desired recombinants?
A. Blue
B. Colorless
C. White
D. Yellowish
Answer: C
Clarification: The Puc8 recombinants will have a non-functional lacZ’ gene due to insertional inactivation hence they will not metabolize X-gal and white colonies will result.

8. What is the compound X-gal?
A. Plasmid
B. Lactose analog
C. Antibiotic
D. Inducer
Answer: B
Clarification: X-gal is a lactose analog which is broken down by enzyme beta-galactosidase to give a product deep blue in color.

9. What is isopropylthiogalactoside?
A. Plasmid of pUC series
B. E.coli strain
C. Antibiotic
D. Inducer
Answer: D
Clarification: IPTG is an inducer of the enzyme beta-galactosidase. Along with X-gal, ampicillin and agar, IPTG is added to induce the enzyme and to perform screening for Puc recombinants.

10. Which of the following selection step does not occur in lac selection system?
A. Ampicillin resistance
B. X-gal plating
C. Agar plating
D. Replica plating
Answer: D
Clarification: In a lac selection system, both ampicillin and presence of beta-galactosidase are tested for on a single agar plate and replica plating is not required.

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