Which is incorrect

Options

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

Answer

To determine which statement regarding the Lac Operon is incorrect, we need to analyze the components and functions of the Lac Operon system. Here’s a step-by-step solution:

### Step 1: Understand the Lac Operon
The Lac Operon is a genetic regulatory system found in E. coli and other bacteria that is responsible for the metabolism of lactose. It consists of several genes that work together to transport and metabolize lactose.

### Step 2: Identify the Components of the Lac Operon
The Lac Operon consists of:
- **Regulatory Gene (I)**: Codes for the repressor protein.
- **Structural Genes**:
- **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 is involved in the metabolism of lactose but is not essential for lactose utilization.

### Step 3: Analyze the Statements
Now, we need to evaluate the statements provided in the question. The key point is to identify which statement incorrectly describes the roles of the genes in the Lac Operon.

### Step 4: Identify the Incorrect Statement
From the analysis:
- The Z gene is essential for lactose metabolism.
- The Y gene is also essential for lactose metabolism as it allows lactose to enter the cell.
- The A gene, while it has a role in metabolism, is not strictly necessary for the basic metabolism of lactose.

If one of the statements claims that all three genes (Z, Y, and A) are required for lactose metabolism, that statement would be incorrect because the A gene is not essential for lactose metabolism.

### Conclusion
The incorrect statement regarding the Lac Operon is the one that asserts that all three genes (Z, Y, and A) are required for lactose metabolism.

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