Question

Ammonia is toxic and must be converted to urea in order to be excreted. The following statements describe the process:
A: ammonia is transported into the liver as either alanine or glutamine.
B: transamination is a key step in the release of ammonia from glutamine.
C: urea is formed and excreted primarily by the kidneys.
D: alanine carries ammonia waste from muscle to the liver; once in the liver, alanine is converted via pyruvate to glucose, which may be returned to the muscle.
E: carbamoyl phosphate is a key intermediate in the conversion of ammonia to urea.
F: urea is ultimately formed by hydrolysis from ornithine

Answer 1

Ans

• Ammonia is transported into liver via carbamoyl phosphate formed from ammonia
• Urea is mainly formed in liver however less amount is also formed in kidney but primary urea excreted from kidney
• Carbamoyl phosphate is formed in first step of urea cycle or intermediate step in formation of urea
• It is fifth or last step of urea cycle, in which arginin is hydrolysed into urea and ornithine
• Transamination is chemical reaction which involves transfer of amino group into keto acid so form new amino acid
• In glucose alanine cycle, ammonium ion is transported from muscles to liver in form of alanine where it can be transaminated again producing pyruvate that can be used for gluconeogenesis yielding glucose that can be send again to the muscle for producing energy.

So among all statement, (D,E) statement is correct