AP BIOLOGY

Detailed explanation-1: -When you eat proteins, the body breaks them down into amino acids. Ammonia is produced from leftover amino acids, and it must be removed from the body. The liver produces several chemicals (enzymes) that change ammonia into a form called urea, which the body can remove in the urine.

Detailed explanation-2: -Arginase hydrolyzes arginine to yield urea, which is released into the blood and excreted by the kidney. Ornithine, the other product of the arginase reaction enters the mitochondrion in exchange for another molecule of citrulline via the same transporter.

Detailed explanation-3: -Aspartate is the source of the second amine group on urea. Recall that aspartate results from the transamination of oxaloacetate and glutamate via aspartate transaminase, which requires vitamin B. Argininosuccinate is converted into arginine via argininosuccinate lyase.

Detailed explanation-4: -Ammonia and carbon dioxide (CO2) react exothermically to produce the carbamate salt, which is then heated to form urea.