Question

In the formation of urea, ammonia and carbon dioxide combine using three amino acids, these are

• A. Orithine, citrulline and alanine
• B. Orithine, citrulline and arginine
• C. Amino acids are not used
• D. Orithine, citrulline and fumaric acid

Answer 1

Answer: (B)

Orithine, citrulline and arginine

Urea is synthesized in the body as a part of the urea cycle, either from the oxidation of amino acids or from ammonia. In this cycle, amino groups donated by ammonia and L-aspartate are converted to urea, while L-ornithine, citrulline, L-argininosuccinate, and L-arginine act as intermediates. Urea production occurs in the liver and is regulated by N-acetylglutamate. Urea is then dissolved into the blood and further transported and excreted by the kidney as a component of urine.