Question

Which of the following is not a characteristic of pBR322 vector?
A. It was the first artificial cloning vector constructed in 1977 by Bolivar and Rodriguez
B. It is the most widely used, versatile and easily manipulated vector.
C. It has two antibiotic resistance genes $te{t^R}$ and $am{p^R}$.
D. It does not have restriction site for Sall.

Answer 1

Hint: pBR322 was the first artificial cloning vector constructed in 1977. It is constructed by Bolivar and Rodriguez. pBR322 DNA is a commonly used plasmid cloning vector in E. coli. It contains the genes for resistance to ampicillin and tetracycline.

Complete answer:
pBR322 was developed by Bolivar and Rodriguez in 1977 in the laboratory of Herbert Boyer at the University of California. They named this plasmid with the number ‘322’ to distinguish from other vectors. Thus, option ‘A’ statement is correct.
pBR322 DNA vector is a commonly used plasmid cloning vector. Thus, option ‘B’ is also correct.
 It contains the genes for resistance to ampicillin and tetracycline antibiotics, and this resistance can be amplified with chloramphenicol and help in selecting recombinant cells from the mixed culture where recombinant and non-recombinant both cells are present. Thus, option ‘C’ is also a correct statement.
pBR322 vector has restriction sites such as Hindlll, EcoRI, BamHI, Sall, Pvill, Pstl, Clal, ori (origin of replication).
From the above discussion, we can conclude that pBR322 has a restriction site for Sall. And option ‘D’ says that Sall is not present in the pBR322 vector.

So, our answer will be option ‘D’.

Note: pBR322 has two antibiotic resistance genes – ampicillin resistance ($am{p^R}$) protein, which is encoded by gene bla, and the other one is tetracycline resistance ($te{t^R}$) protein, which is encoded by gene $te{t^A}$.