What is the minimum number of single-nucleotide substitutions that would be necessary for each of the following amino acid replacements: Phe$\rightarrow$Val; Tyr$\rightarrow$Gly; Met$\rightarrow$Pro; Arg$\rightarrow$Cys?

Question

Quizplus · Accepted Answer

For each amino acid replacement, we need to compare the codons for the original amino acid and the new amino acid and count the number of nucleotide substitutions needed.
For PheF1F1F1S1F1F1F10Val, the codon for phenylalanine (Phe) is UUU and the codon for valine (Val) is GUU. Only one nucleotide substitution (U to G) is needed.
For TyrF1F1F1S1F1F1F10Gly, the codon for tyrosine (Tyr) is UAU and the codon for glycine (Gly) is GGU. Two nucleotide substitutions (U to G and U to G) are needed.
For MetF1F1F1S1F1F1F10Pro, the codon for methionine (Met) is AUG and the codon for proline (Pro) is CCC. Two nucleotide substitutions (A to C and U to C) are needed.
For ArgF1F1F1S1F1F1F10Cys, the codon for arginine (Arg) is CGU and the codon for cysteine (Cys) is UGU. One nucleotide substitution (C to U) is needed.
Therefore, the minimum number of nucleotide substitutions needed for each amino acid replacement are: 1, 2, 2, and 1. The best choice is B.

What Is the Minimum Number of Single-Nucleotide Substitutions That Would →\rightarrow→

What Is the Minimum Number of Single-Nucleotide Substitutions That Would $\rightarrow$