What does a codon consist of?

A codon is defined as a sequence of three nucleotide bases on mRNA (messenger RNA). Each codon corresponds to a specific amino acid or a start/stop signal during the process of protein synthesis. This triplet code is fundamental to the genetic code, which translates the information stored in DNA into the proteins necessary for cellular functions.

In the context of protein synthesis, when ribosomes read these codons, they facilitate the assembly of amino acids into polypeptides, ultimately forming proteins. The specificity of the triplet nature of codons allows for 64 possible combinations from the four nucleotide bases (adenine, uracil, cytosine, and guanine), providing a coding capacity to cover the 20 standard amino acids used in proteins.

Understanding that codons are sequences on mRNA is crucial in molecular biology, as it lays the foundation for grasping how genes are expressed and how cellular functions are regulated through proteins.