Lac operon

The lac operon consists of three adjacent genes required for the transport and of lactose (milk sugar) in the Escherichia coli (E. coli) and some other bacteria. The term operon is used when genes (in this case lacZYA) are co-transcribed into a single messenger RNA. The lac operon is regulated by several factors, one of which is the availability of lactose as an energy source. Control of the lac genes was the first genetic regulatory mechanism to be elucidated, one reason for this is that it is one of the simplest, at least in outline, consisting of simple negative (lac repressor) and positive (CAP) regulatory elements. The lac operon has been considered the canonical example of prokaryotic gene regulation.

References

• {{note|Stryer}} Online textbook: Biochemistry by Jeremy M. Berg, John L. Tymoczko and Lubert Stryer (2002) Published by W. H. Freeman and Co. New York Prokaryotic DNA-Binding Proteins Bind Specifically to Regulatory Sites in Operons