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: -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-3: -(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-4: -Premature stop codons are those that are present in mRNA prior to their normal position in the gene. This means that the message to create the protein of interest is incomplete; thus only incomplete (commonly referred to as truncated) protein is formed.

Detailed explanation-5: -Examples of diseases induced by nonsense mutations include: Cystic fibrosis (caused by the G542X mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) Beta thalassaemia (-globin) Hurler syndrome.