A mutation that converts a sense codon to a stop codon is called what?

A mutation that converts a sense codon to a stop codon is called what?

• A. Nonsense mutation
• B. Missense mutation
• C. Silent mutation
• D. Frameshift mutation

Answer: (A)

When a codon that normally codes for an amino acid is changed into a stop signal, translation ends early and the protein is shortened. This is known as a nonsense mutation. The premature stop means the protein is usually nonfunctional or has reduced function because much of its sequence never gets made. This differs from a missense mutation, which changes one amino acid to another and may alter function without truncating the protein. A silent mutation still codes for the same amino acid, so the protein remains unchanged. A frameshift mutation, caused by insertions or deletions, shifts the reading frame and typically alters many downstream amino acids, often introducing a premature stop as well but through a different mechanism.

When a codon that normally codes for an amino acid is changed into a stop signal, translation ends early and the protein is shortened. This is known as a nonsense mutation. The premature stop means the protein is usually nonfunctional or has reduced function because much of its sequence never gets made.

This differs from a missense mutation, which changes one amino acid to another and may alter function without truncating the protein. A silent mutation still codes for the same amino acid, so the protein remains unchanged. A frameshift mutation, caused by insertions or deletions, shifts the reading frame and typically alters many downstream amino acids, often introducing a premature stop as well but through a different mechanism.