Lac Operon : First Look

The following images attempt to illustrate how the lac operon gene sequence is expressed, and emphasize some of its most important steps. Clicking on each of the thumbnail images will bring up a larger, labeled version of the described scene.

To see the Flash movie for the following sequence of images, click here.

	A simplified E. coli bacterial cell.
	The lac operon gene sequence.
	The repressor molecule, bound to the controlling region.
	Lactose molecules added to the enviroment outside of the cell.
	Lactose molecules bound to the repressor. This releases the repressor from the DNA.
	RNA polymerase transcribing the genes in the lac operon into mRNA.
	Ribosomes translating the mRNA into proteins.
	One of the proteins (yellow) encoded by the lac operon allows lactose to enter the cell at a high rate.
	A second protein (orange) digests the lactose as it enters the cell.
	The lactose molecules bound to the repressor are released.
	Repressor again binds to the controlling region of the DNA.