If two proteins have the same number of amino acids, but they differ from each other by one amino acid, the genes must differ by:
A. one amino acid
B. three codons
C. at least one nucleotide
D. at least three nucleotides
At least one nucleotide.
A codon, which codes for a single amino acid in the final protein, consists of 3 nucleotides.
At least one nucleotide must be changed to code for a different amino acid. Changing 3 nucleotides can also lead to a change in a single amino acid, as long as they're in the same codon.