Answer and explanation:
The operator is a DNA fragment localized between the promoter and structural gene sequences that are able to repress operon transcription. A repressor is a molecule that binds to the operator to inhibit transcription, while an inducer is a molecule that activates transcription by binding either to the repressors or to the activators. A corepressor is a molecule that binds to repressors in order to activate them. A promoter is a DNA sequence localized upstream structural genes which binds to a transcription factor in order to activate operon transcription. Positive regulation is the process by which operon transcription acts as a positive loop, thereby increasing its own transcription, while negative regulation is the process by which operon transcription inhibits its own expression. Allostery refers to the process by which a molecule regulates operon transcription by binding to distal (and therefore non-functional) sites of the operon. Attenuation is a process able to reduce operon transcription and also to block subsequent translation.
