Which type of mutation would most likely have a drastic effect on protein function when it occurs in a coding region?

Which type of mutation would most likely have a drastic effect on protein function when it occurs in a coding region?

• A. Silent mutation
• B. Synonymous mutation
• C. Non-coding region mutation
• D. Frameshift mutation

Answer: (D)

Mutations in a coding region can change the amino acid sequence that a protein is built from, and the way the genetic code is read is critical. A frameshift mutation happens when nucleotides are inserted or deleted in numbers not divisible by three, so the triplet reading frame shifts. Once the frame shifts, every downstream codon changes, producing a string of incorrect amino acids and most often introducing a premature stop. The result is a truncated, nonfunctional or drastically altered protein, which is why this type of mutation tends to have the strongest impact on protein function. In contrast, a silent (synonymous) change alters a codon but still codes for the same amino acid, leaving the protein sequence unchanged. Mutations in non-coding regions can affect gene regulation or splicing but do not directly change the amino acid sequence of the protein itself. Thus, they are less likely to cause an immediate drastic change in the protein’s function compared to a frameshift.

Mutations in a coding region can change the amino acid sequence that a protein is built from, and the way the genetic code is read is critical. A frameshift mutation happens when nucleotides are inserted or deleted in numbers not divisible by three, so the triplet reading frame shifts. Once the frame shifts, every downstream codon changes, producing a string of incorrect amino acids and most often introducing a premature stop. The result is a truncated, nonfunctional or drastically altered protein, which is why this type of mutation tends to have the strongest impact on protein function.

In contrast, a silent (synonymous) change alters a codon but still codes for the same amino acid, leaving the protein sequence unchanged. Mutations in non-coding regions can affect gene regulation or splicing but do not directly change the amino acid sequence of the protein itself. Thus, they are less likely to cause an immediate drastic change in the protein’s function compared to a frameshift.