A good example to illustrate this case is the introduction of resistance genes into bacterial DNA.
If, initially, we have a bacteria sensitive to a given antibiotic, and we transfer to him a gene that will allow it to resist this antibiotic with the help of other bacteria by means of plasmid, the bacterium will acquire resistance against this antibiotic. antibiotic and its phenotype will be changed in the antibiogram.
The protein encoded by the gene will block the activity of the antibiotic, it may be an enzyme that will lyse the antibiotic or a pore that will reject the antibiotic molecule to the outside of the cell ...