Molecular Basis of Inheritance Question 126
126. Which enzymes will be produced in a cell in which there is a nonsense mutation in the lac Y gene?
(a) Lactose permease
(b) Transacetylase
(c) Lactose permease and transcetylase
(d) $\beta$ - galactosidase
Show Answer
Answer : d
Hints & Solution
(d) A nonsense mutation is the one which stops polypeptide synthesis due to formation of a terminating or nonsense codon e.g. ATT (UAA), ATC (UAG), ACT (UGA). The lactose or lac operon of Escherichia coli contains structural genes $(z, y, a)$. If y codes for termination of polypeptide chain then only the product of ’ $z$ ’ gene transcribe to form $\beta$ galactosidase.
