The enzyme missing in Phenylketonuria is

Options

A. Phenyl alanine hydroxylase
B. Phenyl alanine reductuse
C. Phenyl oxidase
D. Phenyl oxidoreductase

Answer

To solve the question regarding the enzyme missing in Phenylketonuria (PKU), we can follow these steps:

### Step 1: Understand Phenylketonuria (PKU)
Phenylketonuria is an inherited metabolic disorder characterized by the inability to metabolize phenylalanine, an amino acid. This condition is caused by a genetic mutation.

**Hint:** PKU is an inherited disorder, which means it is passed down through families.

### Step 2: Identify the Genetic Basis
PKU is caused by a mutation in a specific gene located on chromosome 12. This gene is responsible for encoding an enzyme that is crucial for the metabolism of phenylalanine.

**Hint:** Look for the specific chromosome associated with the disorder.

### Step 3: Determine the Missing Enzyme
The enzyme that is missing in individuals with PKU is responsible for converting phenylalanine into another amino acid called tyrosine. The enzyme that catalyzes this reaction is known as phenylalanine hydroxylase.

**Hint:** Think about the metabolic pathway that involves phenylalanine and what enzyme is needed to convert it to tyrosine.

### Step 4: Analyze the Options
The options provided are:
1. Phenylalanine hydroxylase
2. Phenylalanine reductase
3. Phenyl oxidase
4. Phenyl oxidoreductase

Among these options, the correct answer is phenylalanine hydroxylase, as it is the enzyme that is deficient in PKU.

**Hint:** Compare each option to the function of phenylalanine hydroxylase to determine which one is involved in the conversion of phenylalanine to tyrosine.

### Step 5: Conclusion
The enzyme missing in Phenylketonuria is **phenylalanine hydroxylase**. This deficiency leads to the accumulation of phenylalanine in the blood, which can have toxic effects.

**Final Answer:** The enzyme missing in Phenylketonuria is **phenylalanine hydroxylase**.