Mutations just after the start codon is considered to have more damaging effects than those introduced near the end of the sequence. This is especially true for deletions and insertions.
Which of the following mutations, resulting in an error in the mRNA shortly after the start codon is likely to have the most serious effects on the polypeptide product?
A. Deletion of a single codon
B. Deletion of a single nucleotide
C. Insertion of three nucleotides
D. Substitution of a single nucleotide