Which enzyme will be produced in a cell if there is a nonsense mutation in the lacY gene?
Correct answer: C. β-galactosidase
- A. Transacetylase
- B. Lactose permease and transacetylase
- C. β-galactosidase
- D. Lactose permease
Explanation
A nonsense mutation stops polypeptide synthesis due to the formation of a termination or nonsense codon. In the lac operon, the sequence of structural genes is Z, Y, and A, which respectively code for b-galactosidase, lactose permease, and transacetylase. If the gene Y has a nonsense mutation, gene expression will stop at it, resulting in nonexpression of both gene Y and successive gene A. Thus, only the β-galactosidase enzyme will be produced.
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