« ben fry

the genetic code

This diagram maps three-letter nucleotide sequences to the amino acid that they encode. For instance, the sequence of letters acg in a genome creates the amino acid threonine.

A genome is made up of all the letters (e.g. acagatac) that are read from a sequence of DNA. The letters determine sequences that can become amino acids. Each set of three letters becomes one of twenty amino acids. This is known as the genetic code. For a more thorough description, see the glossary of genetic terms (includes a useful diagram of a chromosome) or the primer on molecular genetics.

This diagram uses a 'T' by default, which refers to Thymine, because most people are familiar with the idea of the genome being associated with the letters, A, C, G, and T. However, it's actually a 'U' for Uracil in this particular context. Pressing 'U' instead of 'T' will switch the letters for better accuracy.

In addition, by adding a small amount of color, the following version of the redesign also shows how hydrophilic (blue) amino acids are arranged in a group at the top of the table, while hydrophobic (white) can be found at the bottom:

A third version includes more information such as the letter codes and full names of the amino acids, along with values for the polar requirement:

The images above are a redesign of the diagrams typically found in most genetics and biology textbooks that are often difficult to read or fail to expose the interesting patterns and relationships in the three letter codes.

For instance, the third letter often has less significance (known as a two or four-fold degenerate).

By simplifying the diagram and removing unnecessary visual elements, it also requires less space than any of the examples below, even while achieving better readability.


Left: Computational Molecular Biology: An Introduction by Clote and Backofen; Middle: Developing Bioinformatics Computer Skills by Gibas and Jambeck; Right: Genomes by Brown and Brown

« ben fry

Developed in Spring 2001 | Updated February 2008 and January 2017
© Ben Fry | Do not reproduce without consent