AP BIOLOGY

Detailed explanation-1: -A nonsense mutation occurs in DNA when a sequence change gives rise to a stop codon rather than a codon specifying an amino acid. The presence of the new stop codon results in the production of a shortened protein that is likely non-functional.

Detailed explanation-2: -A missense mutation occurs when that point mutation causes a different amino acid to be placed from that codon. Because multiple codons code for the same amino acid, not all point mutations will cause a missense mutation.

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: -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-5: -Missense codons (missense mutations): A change in a single amino acid that results from a point mutation in the DNA sequence. Nonsense codons (nonsense mutations): The conversion of a codon from one that encodes an amino acid to one that acts as a stop codon due to a point mutation in the DNA sequence.