AP BIOLOGY

Detailed explanation-1: -A plasmid typically contains an antibiotic resistance gene, which allows bacteria to survive in the presence of a specific antibiotic. Thus, bacteria that took up the plasmid can be selected on nutrient plates containing the antibiotic.

Detailed explanation-2: -Adding an antibiotic resistance gene to the plasmid solves both problems at once – it allows a scientist to easily detect plasmid-containing bacteria when the cells are grown on selective media, and provides those bacteria with a pressure to keep your plasmid.

Detailed explanation-3: -Antibiotic resistance genes are often used as selection markers, which must not be released to the environment upon final product commercialization. For this reason, generation of antibiotic resistance-free vectors is imperative.

Detailed explanation-4: -To survive, germs can develop defense strategies against antibiotics and antifungals called resistance mechanisms. DNA tells the germ how to make specific proteins, which determine the germ’s resistance mechanisms. Bacteria and fungi can carry genes for many types of resistance.

Detailed explanation-5: -Normally, the genes encoding resistance to antibiotics such as ampicillin, chloramphenicol, tetracycline or kanamycin, etc. are considered useful selectable markers. So, an antibiotic resistance gene in a vector usually helps in the selection of transformed cells.