Jacob and Monad studied lactose metabolism in E. coli and Proposed operon concept , which is appplicable for

Options

A. All prokaryotes
B. All prokaryotes and some eukaryotes
C. All prokaryotes and all eukaryotes
D. All prokaryotes and some protozoanes

Answer

**Step-by-Step Solution:**

1. **Understanding the Operon Concept**: The operon concept was proposed by Jacob and Monod while studying lactose metabolism in E. coli. An operon is a cluster of genes under the control of a single promoter and operator, which can be regulated together.

2. **Identifying the Lac Operon**: In E. coli, the lac operon consists of three structural genes (Z, Y, and A) that code for enzymes involved in lactose metabolism. The operon is regulated by the presence or absence of lactose.

3. **Role of the Repressor**: In the absence of lactose, a repressor protein binds to the operator region of the lac operon, preventing RNA polymerase from transcribing the structural genes. This means that the enzymes for lactose metabolism are not produced.

4. **Induction by Lactose**: When lactose is present, it binds to the repressor, causing a conformational change that inactivates the repressor. This allows RNA polymerase to access the promoter and transcribe the structural genes (Z, Y, A), leading to the production of the necessary enzymes for lactose metabolism.

5. **Applicability of the Operon Concept**: The operon concept is primarily applicable to prokaryotes, such as bacteria, where genes can be organized into operons and regulated together. In contrast, eukaryotes typically have monocistronic genes, meaning each gene is transcribed independently.

6. **Conclusion**: Therefore, the operon concept proposed by Jacob and Monod is applicable for prokaryotes, specifically in the context of the lac operon in E. coli.

**Final Answer**: The operon concept proposed by Jacob and Monod is applicable for prokaryotes.

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