1. Which organism has the highest number of vectors?
a) Yeast
b) Mammalian cells
c) E.coli
d) Fungi
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
b) Bacteriophage
c) Plasmid
d) YAC
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?
a) Yip7
b) R6-5
c) pUC8
d) Pbr322
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?
a) Size
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?
a) Ampicillin
b) Kanamycin
c) Lactase
d) Gentamycin
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?
a) 1
b) 2
c) 3
d) 4
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.
a) true
b) false
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?
a) 5-10
b) 50-100
c) 100-200
d) 500-700
Explanation: The high copy number of the plasmid; higher than the previous members of pBR pedigree, was attributed to a chance mutation.