In selecting recombinant bacteria, cells are chosen that are resistant to a specific antibiotic. how are the bacteria made resistant?

The recipient cells actually take up the donor cells DNA and produce the same phenotype as the donor except they were antibiotic resistant from the start so with the combining of these genes the new bacterial cells are like the donors but now antibiotic resistant themselves

When a virus infects a host cell, it uses the cell's machinery to make copies of its own genetic material in a process called replication. finally, during the process of self-assembly, that protein shell and the copies of the virus's genetic material are assembled into new viruses.