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Repressors

Definition

Repressors are proteins that suppress the transcription of a gene. They bind to specific DNA sequences, preventing RNA polymerase from initiating transcription and thus inhibiting gene expression.

Analogy

Think of repressors as a traffic cop at an intersection. When the light is red (repressor is present), cars (RNA polymerase) can't go through, stopping the flow of traffic (gene expression).

Related terms

Operator: A segment of DNA to which a repressor binds. It's like the specific spot where our traffic cop stands.

Inducible Operon: A set of genes transcribed under control of an operator gene; however, transcription happens only in presence of some substances. This is like having a special event that allows cars to pass even when the light is red.

Lac Repressor: A DNA-binding protein which inhibits the expression of genes coding for proteins involved in lactose metabolism in bacteria. It's like a specialized traffic cop who only stops trucks carrying milk products.