Question

A recombinant DNA molecule was created by ligating a gene into a plasmid. By mistake, an exonuclease was added to the tube containing the rDNA. How will this affect the further steps of this technology?

Answer 1

Recombinant DNA technology:

1. Recombinant DNA molecule involves the process of joining two or more different DNA molecules of interest from different species, insertion, and its expression into a suitable host.
2. It is created by ligating the ‘gene of interest’ into a plasmid (vector) with the help of DNA ligase.
3. Plasmids are extrachromosomal small DNA naturally found in bacteria, that self-replicates irrespective of genomic DNA replication.
4. An exonuclease is a type of restriction enzyme that remove nucleotides from the free end of a DNA molecule. They act as proofreaders during DNA polymerization to remove any unusual fragments.
5. Example: Exonuclease I, Xrn1.
6. Adding an exonuclease to the tube containing the rDNA will not affect further steps of this technology. Recombinant DNA is circular with no free ends; hence exonuclease cannot cleave this kind of DNA.