A codon is a sequence of three nucleotides in mRNA that specifies a single amino acid during protein synthesis. This triplet sequence is crucial for translating genetic information into functional proteins, directly determining the amino acid sequence of a polypeptide chain. Accurate codon recognition ensures proper protein formation, which is essential for cellular function and surgical outcomes related to genetic diseases or precision medicine. Misreading or mutations in codons can lead to malfunctioning proteins and various pathologies. Therefore, understanding the codon structure is fundamental in molecular biology and clinical genetics.

Reference: Molecular Biology of the Cell, Alberts et al., 6th Edition.