This set of Vector Biology Multiple Choice Questions & Answers (MCQs) focuses on “Cloning Vectors for E.Coli – 1”.
1. Which organism has the highest number of vectors?
b) Mammalian cells
Explanation: 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
Explanation: 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?
Explanation: 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?
b) Parent organism
c) Restriction site
d) Origin of replication
Explanation: 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?
Explanation: 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
c) 4.3 kb
d) 1 kb
Explanation: 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?
Explanation: 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.
Explanation: 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
c) Auxotrophic mutant selection
d) Plaque morphology selection
Explanation: 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?
Explanation: 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
c) Clustered cloning sites
d) LacZ’ gene
Explanation: 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
c) 15.4 kb
d) 20.4 kb
Explanation: 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
Explanation: 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
c) Restriction sites
d) Tetracycline resistance gene
Explanation: 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.
Explanation: This vector is a modification of M13mp1 and contains a unique restriction endonuclease site resulting from a mutation of GGATCC to GAATCC.
Sanfoundry Global Education & Learning Series – Vector Biology & Gene Manipulation.
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