Question

Presence of more than one recognition sites within the vector will

• A. Facilitates the action of DNA ligase
• B. Complicate the gene cloning
• C. Facilitates the action of restriction enzyme
• D. Facilitates the gene cloning

Answer 1

The correct option is B Complicate the gene cloning

Vector
Vectors are the DNA molecules which can carry the foreign DNA fragment into the host cells for cloning.
Examples include plasmids.

Recognition site
Recognition sites are specific nucleotide sequences, present on the vector DNA, that can be recognised and cleaved by restriction endonucleases for incorporation of the gene of interest.

Gene cloning
Gene cloning is a method of molecular biology used to make multiple copies of a particular gene of interest.
In this method, the gene of interest is inserted into a self replicating vector DNA via genetic engineering to form a recombinant DNA (rDNA). The rDNA is then inserted into a host organism to make clones of the gene of interest.

Consequence of more than one recognition site
If the same restriction enzyme has more than one restriction site in a vector, then the vector will get fragmented upon treatment with the restriction enzyme. This will make the vector unfit for cloning experiments and hence it will complicate the gene cloning.

DNA ligase
DNA ligase is the enzyme that creates the phosphodiester bond between the nucleotides of DNA fragments and joins them together. It helps in the joining of vectors and DNA of interests in genetic engineering.

Final answer
(D) Complicate the gene cloning