​A new strain of bacteria was created by introducing an artificial operon to allow bacterial cells to grow in the presence of iron (Fe⁺⁺). The Fe⁺⁺ operon consists of genes that enable the cells to tolerate increased iron levels.

For the efficient functioning of this operon, the following desirable features were considered:

Which one of the following can be used to develop this operon?

Correct option is C

​Explanation:

1. The Fe⁺⁺ operon must be regulated based on iron availability in the environment.
2. When Fe⁺⁺ is high, bacteria need genes to be expressed to tolerate iron overload.
3. The best regulatory mechanism would involve a repressor protein that is inactivated by Fe⁺⁺, allowing transcription to proceed.
4. This mechanism is similar to the Lac operon, where the repressor becomes inactive when bound to lactose, permitting gene expression.

Thus, the correct mechanism is:

• In the absence of Fe⁺⁺, the repressor remains active, preventing operon expression.
• In the presence of Fe⁺⁺, the repressor is inactivated, allowing transcription of iron-tolerance genes.

This matches Option (c).

Information Booster:

• Operons in Bacteria:
• Lac operon: Repressor is inactivated by lactose (inducible system).
• Trp operon: Repressor is activated by tryptophan (repressible system).
• Fe⁺⁺ operon (artificial) should work like the Lac operon, allowing genes to function when iron is present.
• Iron Regulation in Bacteria:
• Ferric uptake regulator (Fur): A repressor that binds Fe²⁺ and controls iron uptake.
• In high Fe²⁺ conditions, Fur is inactivated, leading to gene expression.