AP BIOLOGY

Detailed explanation-1: -… A nonsense mutation, or its synonym, a stop mutation, is a change in DNA that causes a protein to terminate or end its translation earlier than expected. This is a common form of mutation in humans and in other animals that causes a shortened or nonfunctional protein to be expressed.

Detailed explanation-2: -(NON-sens myoo-TAY-shun) A genetic alteration that causes the premature termination of a protein. The altered protein may be partially or completely inactivated, resulting in a change or loss of protein function.

Detailed explanation-3: -Stop codons are also called nonsense codons because they do not code for an amino acid and instead signal the end of protein synthesis. Thus, nonsense mutations occur when a premature nonsense or stop codon is introduced in the DNA sequence.

Detailed explanation-4: -A nonsense mutation changes the codon for an amino acid into the codon for a “STOP” signal. This completely changes the structure of the protein, because anything after the “STOP” signal is ignored. The ribosome snips off the incomplete protein, and goes on its way.

Detailed explanation-5: -Nonsense: A nonsense variant is another type of substitution. Instead of causing a change in one amino acid, however, the altered DNA sequence results in a stop signal that prematurely signals the cell to stop building a protein.