AP BIOLOGY

Detailed explanation-1: -Silent mutations lead to a change of one of the letters in the triplet code that represents a codon, but despite the single base change, the amino acid that is coded for remains unchanged or similar in biochemical properties. This is permitted by the degeneracy of the genetic code.

Detailed explanation-2: -Silent mutations occur when the change of a single DNA nucleotide within a protein-coding portion of a gene does not affect the sequence of amino acids that make up the gene’s protein.

Detailed explanation-3: -Degeneracy results because there are more codons than encodable amino acids. For example, if there were two bases per codon, then only 16 amino acids could be coded for (4²=16).

Detailed explanation-4: -Silent mutations are only made possible by redundancies in the genetic code. Often several different codons will be translated into the same amino acid.

Detailed explanation-5: -Degeneracy is believed to be a cellular mechanism to reduce the negative impact of random mutations. Codons that specify the same amino acid typically only differ by one nucleotide. In addition, amino acids with chemically similar side chains are encoded by similar codons.