Having been transcribed and translated, it is time for the proteins coded for by the Z and Y genes to play their roles. The two proteins, ß-galactosidase (Z) and permease (Y), can now help bring the lac operon cycle to completion. Clicking on each of the thumbnail images will bring up a larger, labeled version of the described scene.

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	Once the permease has become embedded in the membrane, it allows lactose to flood into the cell at an elevated rate.
	After entering the cell, the lactose is then broken down by ß-galactosidase into the simple sugars glucose and galactose. These simple sugars are used by the cell as food.

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