In the laboratory, recombinant plasmids are commonly introduced into bacterial cells by:
A) electrophoresis—a gentle low-voltage gradient draws the DNA into the cell.
B) infection with a bacteriophage that carries the plasmid.
C) microinjection.
D) mixing plasmids with an extract of broken cells.
E) transformation—heat shock of the cells incubated with plasmid DNA in the presence of CaCl2.
Answer: E