Summary
A cluster of bacterial genes under one promoter and operator, regulated together.
In depth
Operons allow coordinated control of related genes; the operator is a DNA site where a repressor binds and blocks RNA polymerase. They are mainly found in prokaryotes.
Regulation can be negative (repressor) or positive (activator such as CAP).
The idea comes from Jacob and Monod in the 1950s and 60s (Nobel Prize 1965), who used bacterial mutants to deduce how genes are switched. Operons are uncommon in eukaryotes, although C. elegans has some. They allow a single regulatory signal to control a whole pathway, which saves resources.
Control can be inducible (usually off, switched on by a substrate, like lac) or repressible (usually on, switched off by a product, like trp). Activators such as CAP provide positive control. Synthetic gene circuits, including toggle switches and oscillators, build on these designs.
Key idea: an operon is a cluster of genes under one promoter that produces one mRNA, so genes are expressed together.
Frequently asked questions
What is Operon?
A cluster of bacterial genes under one promoter and operator, regulated together.
Which area of biology covers Operon, and how advanced is it?
Operon is one of the 52 topics in Molecular Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Lac Operon, Trp Operon, Promoter.
Can you give an example of Operon?
The his operon controls histidine synthesis.
What should I learn before Operon?
Work through the Beginner topics in Molecular Biology first, such as Central Dogma, DNA Replication, Base Pairing, then return to Operon. Intermediate topics assume the Beginner vocabulary.
What topics are related to Operon?
The closest topics to Operon are Lac Operon, Trp Operon, Promoter, Transcription. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Operon?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Operon. To practise the whole of Molecular Biology, use the Molecular Biology quiz.
How is Operon different from Lac Operon?
Operon: A cluster of bacterial genes under one promoter and operator, regulated together. Lac Operon: An inducible bacterial operon switched on when lactose is present and glucose is scarce. Read both side by side and note what each one explains.
How should I study Operon step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Lac Operon and explain the difference aloud. Finally, take the Molecular Biology quiz and come back to this page for any question you miss.