Question

E. coli cells with a mutated Z gene of the Lac operon cannot grow in a medium containing only lactose as the source of energy because

• A. In the presence of glucose E. coli do not utilize lactose.
• B. They cannot transport lactose from the medium to the cell.
• C. The Lac operon is constitutively active in these cells.
• D. They cannot synthesize functional β-galactosidase

Answer 1

The correct option is D They cannot synthesize functional β-galactosidase

E. coli cells with a mutated Z gene of the Lac operon cannot grow in a medium containing only lactose as the source of energy because they cannot synthesise functional $\beta$-galactosidase.