Question

Which enzyme(s) will be produced in a bacterial cell in which ‘UAG’ is inserted in the ‘lac-y gene’ due to mutation? Choose the correct option:

• A. Transacetylase
• B. Lactose permease
• C. $\beta$-galactosidase
• D. Lactose permease and transacetylase

Hint:

The lac operon includes three genes: lac-z ($\beta$-galactosidase), lac-y (lactose permease), and lac-a (transacetylase). A mutation in one gene may not affect the others.

Answer 1

The Correct Option is C

The lac-y gene encodes lactose permease in the lac operon. UAG is a stop codon, so its insertion in lac-y would truncate lactose permease production. However, the lac-z gene (encoding $\beta$-galactosidase) and lac-a gene (encoding transacetylase) are downstream, but $\beta$-galactosidase can still be produced if the lac-z gene is intact, which is typically the case in such mutations.