Which of the following is not produced by E-Coli in the lactose operon.

Options

A. Beta galactosidase
B. Thiogalactoside transacetylase
C. Lactose dehydrogenase
D. Lactose permease

Answer

To solve the question "Which of the following is not produced by E. coli in the lactose operon?", we need to analyze the components of the lactose operon and the enzymes it produces. Here’s a step-by-step breakdown:

### Step 1: Understand the Structure of the Lac Operon
The lac operon is a genetic unit in E. coli that consists of several genes involved in the metabolism of lactose. It includes:
- A **regulator gene** that produces a repressor.
- An **operator gene** where the repressor binds.
- **Structural genes** that code for enzymes.

### Step 2: Identify the Structural Genes
The structural genes of the lac operon are:
- **Z gene**: Produces **beta-galactosidase** which breaks down lactose into glucose and galactose.
- **Y gene**: Produces **lactose permease** which facilitates the entry of lactose into the cell.
- **A gene**: Produces **thiogalactoside transacetylase**, which is involved in the transfer of acetyl groups.

### Step 3: Analyze the Options
Now, we analyze the options given in the question:
1. **Beta-galactosidase** - Produced by the Z gene.
2. **Thiogalactoside transacetylase** - Produced by the A gene.
3. **Lactose permease** - Produced by the Y gene.
4. **Lactose dehydrogenase** - This enzyme is not produced by the lac operon; it is involved in glycolysis and cellular oxidation.

### Step 4: Conclusion
Based on the analysis, the enzyme that is **not produced by E. coli in the lactose operon** is **lactose dehydrogenase**.

### Final Answer
**Lactose dehydrogenase** is not produced by E. coli in the lactose operon.

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