Exons and introns refer to specific nucleotide base sequences in the genetic code that are involved in producing proteins. Exons are the DNA bases that are transcribed into mRNA and eventually code for amino acids in the proteins. Introns are DNA bases which are found between exons, but are not transcribed. Genes which contain introns are known as interrupted genes.

The discovery of introns and exons occurred in 1977 independently by Richard Roberts and Phillip Sharp. Prior to this time, it was thought that eukaryote genes were strange because they contained more DNA than was transcribed into RNA. These men ran experiments which attempted to identify DNA from the resulting mRNA. It was assumed that the mRNA would have the same base sequence as the DNA from which it was transcribed. This was not the case however. They found stretches of DNA sequences that were...