Commonly known to exist in the genomes of prokaryotes since the 1940s, an operon is a unit of DNA, comprised of a number of clustered genes that are often related by function. The genes in operons are transcribed together by a single promoter into the same mRNA strand, before they are translated into separate proteins  , allowing co-ordination of protein synthesis in response to environmental factors, thereby conserving the cells energy. Genes in an operon are thus either transcribed together or not at all, such as the lac operon in E. coli that is used to hydrolyse lactose into glucose and galactose.
- ↑ Encyclopedia Britannica, Operon. Available at: http://www.britannica.com/EBchecked/topic/429974/operon
- ↑ Lodish, Harvey; Zipursky, Lawrence; Matsudaira, Paul; Baltimore, David; Darnel, James (2000). "Chapter 9: Molecular Definition of a Gene". Molecular Cell Biology. W. H. Freeman. ISBN 0-7167-3136-2
- ↑ ↑ Encyclopedia Britannica, Operon. Available at: http://www.britannica.com/EBchecked/topic/429974/operon