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

**Step-by-Step Solution:**

1. **Understanding Phenylketonuria (PKU)**:
- Phenylketonuria is a genetic disorder characterized by the inability to metabolize phenylalanine due to a deficiency of a specific enzyme. It is inherited in an autosomal recessive manner.

2. **Identifying the Accumulated Substance**:
- In PKU, there is an accumulation of phenylalanine, an amino acid. This accumulation occurs because the body cannot convert phenylalanine into another amino acid, tyrosine.

3. **Identifying the Enzyme Deficiency**:
- The enzyme that is deficient in individuals with PKU is phenylalanine hydroxylase. This enzyme is responsible for the hydroxylation of phenylalanine to form tyrosine.

4. **Understanding the Process**:
- Hydroxylation is a chemical process where a hydroxyl group (-OH) is added to a compound. In this case, phenylalanine undergoes hydroxylation to become tyrosine.

5. **Evaluating the Options**:
- The question provides four options regarding the function of the enzyme:
- Option 1: Causes hydroxylation of phenylalanine to tyrosine (Correct)
- Option 2: Causes hydroxylation of tyrosine to form phenylalanine (Incorrect)
- Option 3: Causes carboxylation of phenylalanine to form tyrosine (Incorrect)
- Option 4: Causes carboxylation of tyrosine to form phenylalanine (Incorrect)

6. **Conclusion**:
- The correct answer is that in phenylketonuria, the patient has a deficiency of the enzyme that causes hydroxylation of phenylalanine to tyrosine.

**Final Answer**: The enzyme that is deficient in phenylketonuria is phenylalanine hydroxylase, which causes hydroxylation of phenylalanine to form tyrosine.

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