Question

What is true for E. coli with lac-z gene?

• A. They cannot synthesize permease.
• B. They cannot synthesize functional beta galactosidase.
• C. They cannot synthesize transacetylase.
• D. They cannot transport lactose from the medium into the cell.

Answer 1

Answer: (A)

They cannot synthesize permease.

The gene product of lac-Z is β-galactosidase which cleaves lactose, a disaccharide, into glucose and galactose. Lac-Y encodes Beta-galactoside permease, a protein that becomes embedded in the cytoplasmic membrane to enable transport of lactose into the cell. The E.coli with lac-z gene cannot synthesize permease because permease is synthesized by the lac-Y gene.

So, the correct answer is 'They cannot synthesize permease'.