Question

Which best describes an inducible operon?

• A. The tryptophan gene, in which the presence of tryptophan functions as a corepressor to prevent its own transcription.
• B. The lac gene, in which the repressor, preventing the synthesis of the enzymes that degrade lactose, is deactivated by the presence of lactose.
• C. A type of gene expression mostly seen in eukaryotes.
• D. All of the above.

Answer 1

The correct option is B The lac gene, in which the repressor, preventing the synthesis of the enzymes that degrade lactose, is deactivated by the presence of lactose.

Inducible type of operon is when the gen is switched on in response to the presence of substrate. (inducer).

It is found in catabolic pathways. E.g. Lactose operon or Lac Operon. Lac operon consists of following components-

1. Structural genes.
2. Operator genes
3. Promotor genes
4. Reguator gens
5. Reresor
6. Inducer.

In lac operon lactose acts as an inducer and when it binds to the regulatory gene and the operon is functioning.

So, the correct option is 'The lac gene, in which the repressor, preventing the synthesis of the enzymes that degrade lactose, is deactivated by the presence of lactose.'