Click to enlarge Photo: NIH
The lac operon is a favorite of microbiology and biology textbooks, used to explain transcription, regulation, and catabolism. Here's my quick synopsis of the regulation involved, making sure the cell only transcribes genes that encode lactose-eating enzymes only when it is physiologically necessary. But first, a GENETICS crash course in biology:
An operon is a group of genes transcribed as a single unit. It's like buying Orange Box. There's five separate games, but they're all purchased at once in a neat box. The same thing with an operon. If the operon is ON, you get all of the genes activated. If the operon is OFF, none of the genes are activated.
RNA polymerase is a protein that reads DNA molecules in the cell to make RNA. This RNA is then read again by ribosomes to direct the synthesis of specific proteins..