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Question

Which enzyme will be produced in a cell where a nonsense mutation is present in the lac operon?

Answer

In genetics, the mutation in which a sense codon that corresponds to one of the twenty amino acids is changed to a chain terminating codon, i.e., UAA, UAG, UGA, is known as nonsense mutation.

The structure of lac operon is as follows:

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If the nonsense mutation takes place at the operator, then simultaneous constitutivity for all the products of the operon will take place. Thus, this explains that operon acts as a unit of genetic expression.

If nonsense mutation takes place in the lac y, lac z or lac a gene, the mRNA of the gene in which the mutation has occured, will not be translated into enzyme and hence, no protein will be produced. If nonsense mutation occurs in all of the three genes, then no lac enzymes will be formed.

Thus, no new enzymes will be formed in a cell due to nonsense mutation.