In your laboratory, you use plasmids that carry the amp^R gene to transform E. coli cells that lack this gene. The illustration below outlines the major steps in this procedure.

You also prepare a second group of E. coli cells as a control to verify that E. coli will not grow on agar with ampicillin unless it is transformed, and that nothing in the procedure itself affects the survival of E. coli. The procedure is the same for both groups of cells except in step 2, where you add amp^R plasmids to the experimental cells but not to the control cells.

See an animation of the process at the cellular level.

To be sure you've understood what happens during bacterial transformation, continue to Place the Stages of Transformation in Order.