Amino acids participating in ornithine cycle are

Options

A. arginine, lysine and citrulline
B. ornithine, arginine and glycine
C. arginine, citrulline and ornithine
D. ornithine, arginine and glutamic acid

Answer

To answer the question regarding the amino acids participating in the ornithine cycle, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Ornithine Cycle**: The ornithine cycle, also known as the urea cycle, is a series of biochemical reactions that convert ammonia to urea for excretion. It primarily occurs in the liver.

2. **Identify Key Amino Acids**: The main amino acids involved in the ornithine cycle are:
- **Ornithine**: This is a key substrate that enters the cycle.
- **Citrulline**: This is formed from ornithine and is a crucial intermediate in the cycle.
- **Arginine**: This amino acid is produced in the cycle and can be converted back to ornithine.

3. **Recognize Additional Participants**: The cycle also involves aspartate, which provides one of the amino groups necessary for the conversion of citrulline to arginine.

4. **Summarize the Participants**: The amino acids that participate in the ornithine cycle include:
- **Ornithine**
- **Citrulline**
- **Arginine**
- **Aspartate** (though not directly asked, it plays a role in the cycle)

5. **Conclusion**: Therefore, the primary amino acids participating in the ornithine cycle are **ornithine, citrulline, and arginine**.

### Final Answer:
The amino acids participating in the ornithine cycle are **ornithine, citrulline, and arginine**.

---