Why Are There 64 Codons For 20 Amino Acids: Decoding Genetic Complexity

Researchers found that in RNA, a triplet code, also known as a codon, is the smallest combination of nucleotides (A, C, G, and U) that can encode all 20 amino acids. This triplet code consists of three bases, and this choice isn’t arbitrary. It stems from the fact that there are four possible bases at each of the three positions. Therefore, the total number of possible combinations can be calculated by multiplying these options together (4 × 4 × 4), resulting in 64 possible codons. This 64-codon system provides the necessary diversity to encode all the different amino acids required for protein synthesis.

The genetic code consists of 64 codons, a result of the various combinations of the four nucleic acid bases. This genetic code exhibits a degenerate nature, which means that multiple codons can represent the same amino acid. As a result, out of the 64 codons available, 61 codons have been assigned specific amino acids, encoding the full set of 20 amino acids found in biological proteins. This degeneracy allows for redundancy in the genetic code, providing a degree of robustness against mutations and ensuring the accuracy of protein synthesis.

The phenomenon of having 64 codons but only 20 amino acids is known as the degeneracy of the genetic code. To illustrate this concept, let’s consider an example: there are six different codons that can code for three specific amino acids. This alone accounts for 18 out of the 64 possible codon combinations. This concept helps explain the apparent redundancy and versatility of the genetic code, where multiple codons can encode the same amino acid. This principle was first described on September 28, 2015.