Question

If the codon AAA is changed to AAG, it still codes for the amino acid lysine; this is an example of a

A) nonsense mutation.
B) silent mutation.
C) dimer formation.
D) frameshift mutation.
E) missense mutation.

Answer 1

The codon change from AAA to AAG, both coding for lysine, is a silent mutation because it does not change the resulting amino acid in the protein sequence.

Step-by-step explanation:

A change from the codon AAA to AAG, both encoding for the amino acid lysine, does not alter the amino acid sequence of the produced protein. Hence, this change is an example of a silent mutation. This is because silent mutations result in a different codon but still code for the same amino acid, leaving the protein's function unaffected. Unlike nonsense mutations, which introduce a premature stop codon and can result in truncated, non-functional proteins, silent mutations maintain the integrity of the amino acid sequence.

The genetic code is redundant, which means some amino acids are coded for by more than one codon, and this redundancy is the reason why silent mutations do not alter the protein product. It is important to differentiate between silent mutations and more drastic mutations like frameshift mutations, which can occur due to the deletion or insertion of a nucleotide and result in a completely altered amino acid sequence from the point of mutation.