If a codon changes from coding for leucine to coding for phenylalanine, this mutation is

If a codon changes from coding for leucine to coding for phenylalanine, this mutation is

• A. Missense mutation
• B. Nonsense mutation
• C. Silent mutation
• D. Frameshift mutation

Answer: (A)

A single nucleotide change that substitutes one amino acid for another is a missense mutation. In this case, the codon previously coding for leucine now codes for phenylalanine, so the protein’s sequence is altered at that position. This can affect folding or function, depending on the proteins and the specific substitution. It’s not a nonsense mutation because no stop codon is created. It’s not a silent mutation because the amino acid actually changes. It’s not a frameshift mutation because the reading frame remains intact and no nucleotides are inserted or deleted to shift downstream codons.

A single nucleotide change that substitutes one amino acid for another is a missense mutation. In this case, the codon previously coding for leucine now codes for phenylalanine, so the protein’s sequence is altered at that position. This can affect folding or function, depending on the proteins and the specific substitution. It’s not a nonsense mutation because no stop codon is created. It’s not a silent mutation because the amino acid actually changes. It’s not a frameshift mutation because the reading frame remains intact and no nucleotides are inserted or deleted to shift downstream codons.