Question

Which of the following limits the effects of mutations in a specific gene sequence?

• A. Each amino acid has only one codon.
• B. Most amino acids have more than one codon.
• C. A few codons are common to more than one amino acid.
• D. There are three codons for each amino acid.

Answer 1

The correct option is B Most amino acids have more than one codon.

As per the universal genetic code there are 64 codons (61 coding codons) for the 20 amino acids that exist. This is because most of the amino acids are coded for by more than a single codon. Each codon however, is specific for a single amino acid. No two amino acids would have the same codon coding for them. For instance, in the codon UUU, if the third base gets replaced with a C, the codon becomes UUC. Nevertheless, both the codons code for phenylalanine and hence, there’s no harm in such a mutation. This explains the advantage of having multiple codons for most amino acids.