An inducible bacterial operon switched on when lactose is present and glucose is scarce.
Genes lacZ, lacY and lacA metabolise lactose. Without lactose, the LacI repressor binds the operator. Allolactose binds the repressor and releases it. When glucose is low, cAMP-CAP boosts transcription further, so the operon is fully active only if lactose is present and glucose absent.
Jacob and Monod won the 1965 Nobel Prize.
An inducible bacterial operon switched on when lactose is present and glucose is scarce.
Lac 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 Operon, Trp Operon, Gene Expression.
A constitutive lacI mutant expresses the genes all the time.
Work through the Beginner topics in Molecular Biology first, such as Central Dogma, DNA Replication, Base Pairing, then return to Lac Operon. Intermediate topics assume the Beginner vocabulary.
The closest topics to Lac Operon are Operon, Trp Operon, Gene Expression, Telomerase. Comparing them side by side is a good way to see how the ideas connect.
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Lac Operon. To practise the whole of Molecular Biology, use the Molecular Biology quiz.
Lac Operon: An inducible bacterial operon switched on when lactose is present and glucose is scarce. Operon: A cluster of bacterial genes under one promoter and operator, regulated together. Read both side by side and note what each one explains.
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 Operon and explain the difference aloud. Finally, take the Molecular Biology quiz and come back to this page for any question you miss.
A cluster of bacterial genes under one promoter and operator, regulated together.
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