Question

Which of the following best describes the effect of a nonsense mutation on a gene? group of answer choices

O it has no effect on the amino acid sequence of the encoded protein.
O it alters the reading frame of the mrna.
O it renders the gene completely useless/ineffective.
O it introduces a premature stop codon into the mrna.
O it changes the amino acid in the encoded protein.

Answer 1

A nonsense mutation introduces a premature stop codon into the mRNA, leading to a truncated protein that is typically non-functional. The answer is option D.

Step-by-step explanation:

A nonsense mutation refers to a change in the DNA sequence that converts a codon for an amino acid into a stop codon within a gene's coding sequence. This type of mutation leads to the production of an mRNA that contains a premature stop codon. As a result, translation of the mRNA is terminated earlier than it should be, which typically produces a truncated, and often non-functional protein. The severity of the effect on the gene's functionality depends on where in the coding sequence the nonsense mutation occurs; the earlier it happens, the more likely the resultant protein will be non-functional.

The correct answer to the question is, therefore: it introduces a premature stop codon into the mRNA. A nonsense mutation does not necessarily render the gene completely useless/ineffective in every case, as some truncated proteins can retain partial function or the organism may have compensatory mechanisms. However, it often does lead to a significant loss of function.