Question

A plasmid without a selectable marker was chosen as vector for cloning a gene. How does this affect the experiment?

Answer 1

A plasmid with a selectable marker (antibiotic resistance conferring gene) allows the selection of transformed or recombinant cells from the non-transformed or non-recombinant cells because in a population of cells, all the cells do not take up the plasmid. So, the selectable marker allows the transformed cell to live in the presence of antibiotics in the medium and non-transformed cell will perish. But without the selectable marker, the selection of the transformed cells will not be possible and in the presence of antibiotics, even the transformed cells will perish. Hence, it becomes a futile exercise.