How do you insert a gene into a plasmid?
A gene is nothing but a portion of dna coding for a specific protein.
Basically the gene to be incorporated into the plasmid is known as a DNA insert.
The gene of interest or the DNA insert, is initially cleaved from the genomic source of an organism using an enzyme known as the restriction endonuclease or is artificially synthesized in the in the laboratory. Even the circular plasmid is cleaved using the same or different restriction enzyme based on the requirement. (the cleaving of the circular plasmid is to create space to insert the DNA insert).
Now the DNA insert is attached to the plasmid using an effective gluing enzyme known as the DNA ligase (usually used type of DNA ligase enzyme is T4 ligase from bacteriophage).
And the complete recombinant vector, i.e., DNA insert + plasmid, is constructed.