All the following are correct , except :

Options

A. i-gene codes for the repressor of lac operon
B. z-gene codes for the beta-galactosidase
C. y-gene codes for transacetylase
D. three gene products are required for

Answer

To solve the question, we need to analyze the statements provided about the lac operon and identify the incorrect one. Here’s a step-by-step breakdown:

### Step-by-Step Solution:

1. **Understand the Lac Operon Structure**:
- The lac operon consists of several components: a regulatory gene (I gene), three structural genes (Z, Y, and A), and an operator region.
- The I gene codes for the repressor protein that inhibits the transcription of the structural genes when lactose is absent.

2. **Identify the Function of Each Gene**:
- **I gene**: Codes for the repressor protein.
- **Z gene**: Codes for beta-galactosidase, which breaks down lactose into glucose and galactose.
- **Y gene**: Codes for permease, which facilitates the entry of lactose into the cell.
- **A gene**: Codes for transacetylase, which has a role in the metabolism of lactose.

3. **Analyze the Statements**:
- **Statement 1**: "I gene codes for the repressor of lac operon." - This is correct.
- **Statement 2**: "Z gene codes for beta-galactosidase." - This is correct.
- **Statement 3**: "Y gene codes for transacetylase." - This is incorrect. The Y gene actually codes for permease.
- **Statement 4**: "Three gene products are required for the metabolism of lactose." - This is correct.

4. **Identify the Incorrect Statement**:
- The incorrect statement is the third one: "Y gene codes for transacetylase." This is not true; the Y gene codes for permease.

### Final Answer:
The incorrect statement is: "Y gene codes for transacetylase."

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