Definition of "exon" [ex•on]

• A sequence of DNA that codes information for protein synthesis that is transcribed to messenger RNA. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Genes recombine by fusing in whole or in part, by a process known as exon shuffling exons are the separate stretches of code that are used to make one protein in split genes."
• "Perhaps the exon is a protogene — one that's effectively dormant until it's switched on by some external factor."
• "The abnormal FSHR contained a deleted sequence of protein called exon 2 that is an important part of the protein that binds the FSH; FSHR with the exon 2 deletion was only detected in women younger than 35 who had a poor response to FSH and yielded less than four oocytes in a follicle stimulating cycle."