Question

Which one among the following is not a cloning plasmid?
A. pBAD 18-Cam
B. pBSCK
C. pUC 18
D. pET

Answer 1

Hint: A DNA molecule in which a foreign DNA is integrated which can replicate it within itself to produce numerous clones of recombinant DNA is known as a cloning vector.

Complete answer:
A single piece of DNA that is taken from a virus, a plasmid, and from a cell of higher organisms is known as a cloning plasmid. It can be stably maintained in an organism in which a fragment of foreign DNA can be transferred or can be inserted for cloning purposes. They have an appropriate cloning site and selectable markers. They have a specific DNA sequence that acts as the origin of replication or ORI. They should have some restriction sites that enable them to break up certain sequences with a restriction endonuclease. They have multiple cloning sites.

A circular piece of DNA that contains the origin of replication, and has appropriate regulatory regions located at 5’ to the site in which the gene of interest is inserted which is a criterion for selection. The origin of replication is an important site that assures the replication of plasmid within the host bacterium. pUC 18 is a small, high copy cloning plasmid for the replication of Escherichia coli and it has an ampicillin resistance gene and pMB 18 origin of replication from pBR 322. It can be used for cloning and expression purposes.

Hence, the correct option is C, i.e., pUC 18

Note: pUC 18 and pUC 19 plasmids enable successful cloning of larger fragments because it has multiple cloning sites at lacZ' region and recombinant plasmids can be screened by blue/white screening using agar plates containing IPTG and X-Gal.