Imagine that you have set up a genetic screen to identify E. colimutants that cannot metabolize the amino acid tryptophan for energy. Beginning with a master plate containing many colonies, you prepare replica plates on medium with glucose or tryptophan as the only energy source. You would look for colonies that ________.
A) can grow only on the plates with glucose
B) cells would expend significantly more energy
C) it cannot bind to the inducer
D) allolactose binds to the repressor protein
