In a protein-coding region, any amino acid can be replaced with any other amino acid by a mutation that replaces a single nucleotide for another.

Question

Quizplus · Accepted Answer

This statement is not completely true. Some substitutions of amino acids may be more likely to occur due to the genetic code, which dictates which nucleotide triplets code for which amino acids. For example, a substitution of the first nucleotide in a codon is more likely to result in a conservative substitution (i.e. a similar amino acid) than a substitution of the third nucleotide. Additionally, certain amino acids may be more critical for the structure or function of the protein, making substitutions of those amino acids less likely to be successful.

In a Protein-Coding Region, Any Amino Acid Can Be Replaced