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The Lac Operon Simplified

Lac operon
The lac operon is a group of genes that controls lactose breakdown

The Lac operon can be simplified as a group of genes required for the transport and breakdown of lactose into energy in E. Coli. Before you heard about operons you probably just thought about a single gene being transcribed into RNA and eventually working protiens. Operons are more than one gene that has been grouped into the same location because they are needed for similar functions in a cell.

A well studied operon is the Lac Operon found in the bacteria E. Coli. When lactose is abundant and enters E. Coli, the lac operon must be activated to breakdown and use the lactose.

Activating the Lac Operon

The lac operon is known as an inducible system. Since the Lac Operon is an inducible system, it will only activate in the presence of a “key” molecule. The key molecule, lactose, induces the Lac operon to be activated.

Top: The repressor prevents the genes in the lac operon from being transcribed by RNA polymerase.

Bottom: Lactose binds to the repressor and causes it to be removed. RNA polymerase can now access the genes in the Lac Operon and transcribe them in RNA and eventually proteins.

Functions of Lac Genes

Lac Z, Lac Y, and Lac A represent B-galactosidase, Lactose permease, and thiogalactoside transacetylase.
[table] Protein,Function
B-galactosidase,breaks lactose into glucose and galactose
Lac Permease, Channel protein that allows lactose to enter the cell
thiogalactoside transacetylase, function not currently understood(this is science)


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