Worked example 6 — a gene of 150 base pairs

A gene X has 150 nucleotide pairs. Number of codons = 150/3 = 50, so the protein has at most 50 amino acids (49 if one of the codons is a stop codon). For a polypeptide of 21 amino acids, at least 63 nucleotides are needed in the coding part of the mRNA (66 if the stop codon is included).