How many types of operons are there?

Operon:

1. An operon is a cluster of functionally-related genes that are controlled by a single promoter, an operator and a repressor.
2. Operons can be of two types:
   1. Inducible –
      1. This type of operon is switched on in the presence of an inducer, e.g. Lac operon.
   2. Repressible –
      1. It is usually present in anabolic pathways.
      2. The operon is active and the functional product or enzyme is present normally in the cell.
      3. When the end product reaches the maximum value, the operon is turned off. E.g. Trp operon