exon

Term: exon

Origin: expressed region

Coined: by American biochemist Walter Gilbert (1932- )  in 1978 who wrote:

“The notion of the cistron, the genetic unit of function that one thought corresponded to a polypeptide chain, now must be replaced by that of a transcription unit containing regions which will be lost from the mature messenger -- which I suggest we call introns (for intragenic regions) -- alternating with regions which will be expressed -- exons. The gene is a mosaic: expressed sequences held in a matrix of silent DNA, an intronic matri”.  (Gilbert, W. (1978) Why genes in pieces? Nature 271: 501)

Definition:

An exon is a DNA sequence that is represented in the mature form of an complementary RNA molecule. In many genes, each exon codes information for protein synthesis but in modern sence exons are also untranslated