An individual affected by phenylketonuria lacks an enzyme that converts the amino acid `"_____"` into `"_____"`

Options

A. tyrosine, pheylalanine
B. phenylalanine, tyrosine
C. homogentisic acid, phenylalanine
D. homogentisc acid, tyrosine

Answer

To solve the question, we need to identify the amino acids involved in the condition known as phenylketonuria (PKU). Let's break it down step by step.

### Step-by-Step Solution:

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

2. **Identifying the Enzyme:**
- The enzyme that is lacking in individuals with PKU is called **phenylalanine hydroxylase**. This enzyme is crucial for the conversion of one amino acid to another.

3. **Amino Acids Involved:**
- The amino acid that accumulates in individuals with PKU is **phenylalanine**. This is because, without the enzyme, phenylalanine cannot be converted into another amino acid.
- The amino acid that phenylalanine is supposed to be converted into is **tyrosine**.

4. **Final Answer:**
- Therefore, the individual affected by phenylketonuria lacks an enzyme that converts the amino acid **phenylalanine** into **tyrosine**.

### Answer:
An individual affected by phenylketonuria lacks an enzyme that converts the amino acid **phenylalanine** into **tyrosine**.

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