question_answer

E-coli cells with a mutated Z gene of lac operon can not grow in medium containing only lactose as source of energy because

A)  They are unable to transport lactose from medium into cell

B)  The lac operon is constitutively active in these cells

C)  They can not synthesize functional B galactosidase

D)  In the presence of glucose, E.Coli do not utilize lactose