In the ornithine cycle, which of the following wastes are removed from the blood?
CO2 and ammonia
Urea is formed in the liver by a cyclic process called the urea cycle. Three amino acids, ornithine, citrulline and arginine, participate in this process. Ornithine combines with ammonia and carbon dioxide to form citrulline and water. Citrulline combines with more ammonia to form arginine and water. Arginine is decomposed to form urea and ornithine in the presence of the enzyme arginase and water. Ornithine is set free for reuse in the urea cycle.