Table of mRNA Codons and Properties of the Genetic Code

By Anne Marie Helmenstine, Ph.D.

This is a table of mRNA codons for the amino acids and a description of the properties of the genetic code.

Genetic Code Properties

1. There is no ambiguity in the genetic code. This means each triplet codes for only one amino acid.

    

2. The genetic code is degenerate, which means there is more than one triplet code for many of the amino acids. Methionine and tryptophan each are coded by just one triplet. Arginine, leucine, and serine each are coded by six triplets. The other 15 amino acids are coded by two, three, and four triplets.

    

1. There are 61 triplet codes for amino acids. Three other triplets (UAA, UAG, and UGA) are stop sequences. The stop sequences signal chain termination, telling the cellular machinery to stop synthesizing a protein.

    

2. The degeneracy of the code for the amino acids coded by two, three, and four triplets is only in the last base of the triplet code. As an example, glycine is coded by GGU, GGA, GGG, and GGC.

    

3. Experimental evidence indicates the genetic code is universal for all organisms on Earth. Viruses, bacteria, plants, and animals all use the same genetic code to form proteins from RNA.

Table of mRNA Codons and Amino Acids