BioCoach Activity

Concept 3: The lac Operator

The operator is a short region of DNA that lies partially within the promoter and that interacts with a regulatory protein that controls the transcription of the operon.

Here's an analogy. A promoter is like a doorknob, in that the promoters of many operons are similar. An operator is like the keyhole in a doorknob, in that each door is locked by only a specific key, which in this analogy is a specific regulatory protein.