Question

Which enzymes will be produced in a cell in which these is a nonsense mutation in the lac Y gene ?

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

Answer 1

The correct option is D $\beta$ - galactosidase

A nonsense mutation is the type of mutation in which a sense codon that corresponds to one of the twenty amino acids specified by the genetic code is changed to a chain-terminating codon. A nonsense mutation in the lacY gene will make it produce a non-functional permease. Also, the stop codon will be added after the lac Z gene and hence, beta-galactosidase will be produced. Therefore, neither permease nor transacetylase will be produced, and only beta-galactosidase will be produced.

So, the correct answer is 'β - galactosidase'.