Question

Explain the role of Lactose as an inducer in Lac-operon.

Answer 1

1. A few molecules of lactose enter into the cell by an enzyme permease.
2. A small amount of this enzyme is present even when the operon is switched off.
3. A few molecules of lactose, act as an inducer and bind to the repressor.
4. This repressor–inducer complex fails to join with the operator gene, which is then turned on.
5. Structural genes produce all enzymes. Thus, lactose acts as an inducer of its own breakdown.
6. When the inducer level falls, the operator is blocked again by a repressor. So structural genes are repressed/inactivated again. This is negative feedback.