Which enzyme/s will be produced in a cell in which there is a nonsese mutation in the lac Y gene

Options

A. Transacetylase
B. Lactose permese and transacetylase
C. `beta`-galactosidase
D. Lactose permease

Explanation

To answer the question about which enzymes will be produced in a cell with a nonsense mutation in the lacY gene, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Lac Operon Structure**:
The lac operon consists of three structural genes: lacZ, lacY, and lacA. Each of these genes encodes a specific enzyme involved in lactose metabolism.
- **lacZ**: Encodes beta-galactosidase, which breaks down lactose into glucose and galactose.
- **lacY**: Encodes lactose permease, which is responsible for transporting lactose into the cell.
- **lacA**: Encodes transacetylase, which is involved in the metabolism of lactose.

**Hint**: Remember the functions of each gene in the lac operon.

2. **Define Nonsense Mutation**:
A nonsense mutation is a type of mutation where a sense codon (which codes for an amino acid) is changed into a stop codon. This results in premature termination of protein synthesis, leading to a non-functional protein.

**Hint**: Think about how a stop codon affects protein synthesis.

3. **Identify the Impact of Nonsense Mutation in lacY**:
In the case of a nonsense mutation in the lacY gene, the translation of the lactose permease protein will be prematurely terminated. This means that the lactose permease enzyme will not be produced or will be non-functional.

**Hint**: Consider what happens to the protein product when a gene is mutated to produce a stop codon.

4. **Determine the Production of Other Enzymes**:
The lacZ gene, which encodes beta-galactosidase, is located upstream of lacY. Therefore, the transcription and translation of lacZ will still occur normally, producing the beta-galactosidase enzyme. The lacA gene will also likely be transcribed and translated, producing transacetylase.

**Hint**: Recall that the transcription of genes in an operon can be independent of one another if they are upstream.

5. **Conclusion**:
In a cell with a nonsense mutation in the lacY gene, the following enzymes will be produced:
- **Beta-galactosidase** (from lacZ)
- **Transacetylase** (from lacA)
However, **lactose permease** (from lacY) will not be produced or will be non-functional.

**Final Answer**: The enzymes produced will be beta-galactosidase and transacetylase.

### Summary of the Correct Answer:
- **Beta-galactosidase** (produced from lacZ)
- **Transacetylase** (produced from lacA)
- **Lactose permease** (produced from lacY) will not be functional due to the nonsense mutation.