The Genetic Code

Abstract

The key to many of the important processes in the cell is information flow. Information is permanently archived in the nucleus and temporary copies of that information are made by carrying out transcription to create RNA. Some RNAs can act directly as enzymes, structural molecules, or even transport units that carry amino acids, but the information flow in the cell goes far beyond that. The genetic code uses only four letters but manages to contain far more information than can be spelled out with four letters by using the same type of encoding mechanism used by Morse code: combining three DNA bases together and reading them as if they were a single letter. One breakthrough in understanding the genetic code came when scientists figured out how those three bases in a row spell out each “letter” in the genetic code. Just as Morse code combinations of dashes and dots can designate the 26 letters of the English alphabet, four genetic building blocks when combined in groups of three can produce 64 different letters in the alphabet of the genetic code. Each three-unit letter, called a codon, specifies one of the building blocks that make up proteins, called amino acids.