In phenylketonuria, the patient has a deficiency of any enzymes which

Options

A. causes hydroxylation of phenylalanine to form tyrosine
B. causes hydroxylation of tyrosine to form phenylalanine .
C. causes carboxylation of phenylalanine to form tyrosine
D. causes carboxylation of tyrosine to form phenylalanine

Answer

To solve the question regarding the deficiency of enzymes in phenylketonuria (PKU), we can break down the problem into the following steps:

### Step-by-Step Solution:

1. **Understanding Phenylketonuria (PKU)**:
- PKU is a genetic disorder that results in the inability to metabolize phenylalanine, an amino acid found in many protein-containing foods.

2. **Identifying the Enzyme Involved**:
- The key enzyme that is deficient in PKU is **phenylalanine hydroxylase**. This enzyme is responsible for converting phenylalanine into tyrosine through a hydroxylation reaction.

3. **Consequences of the Enzyme Deficiency**:
- Due to the deficiency of phenylalanine hydroxylase, phenylalanine accumulates in the body. This accumulation can lead to serious health issues, including intellectual disability and other neurological problems.

4. **Understanding the Biochemical Pathway**:
- Normally, phenylalanine is hydroxylated to form tyrosine. In PKU, since this reaction cannot occur, phenylalanine levels rise, and tyrosine levels drop, leading to a metabolic imbalance.

5. **Conclusion**:
- Therefore, the answer to the question is that in phenylketonuria, the patient has a deficiency of the enzyme **phenylalanine hydroxylase**, which causes the hydroxylation of phenylalanine to form tyrosine.

### Final Answer:
In phenylketonuria, the patient has a deficiency of the enzyme **phenylalanine hydroxylase**, which is responsible for the hydroxylation of phenylalanine to form tyrosine.

---