Question

In recombinant DNA technology a plasmid vector must be cleaved by
A) The same enzyme that cleaves the donor gene
B) Modified DNA ligase
C) A heated alkaline solution
D) Four separate enzymes

Answer 1

Hint: Plasmids are the extra chromosomal region of DNA. They are circular DNA and are self replicating in nature. They are dependent on the host for replication. They are widely used in recombinant DNA technology.

Complete Answer:
- Recombinant DNA technology is the process of joining together desired DNA fragments obtained by the host into a host organism using a vector called the plasmids.
- Plasmids are the vectors which are a circular DNA molecule. They have restriction sites in them which can be recognised by the restriction enzymes.
- In RDT, the desired site in the circular DNA (plasmid) is cleaved by using restriction enzymes. The same restriction is used to cleave the same sequence of DNA of the donor.
- Then the donor gene is ligated by the help of DNA ligase enzymes in the plasmid. The plasmid is placed in a living cell where it replicates.

A heated alkaline solution denatures the enzymatic activity.

Thus the correct answer is (A). A plasmid vector must be cleaved by the same enzyme that cleaves the donor gene.

Note: RDT was developed in the 1970s. The recombinant DNA technology has a wide range of applications in making hybrids. The hybrids are more stable. It is used in human therapeutics as well.