Integration with TCA cycle — Flashcards

Flashcard 1: In the liver, _____ may transfer a molecule of NH3 to the urea cycle, reforming α-ketoglutarate

Answer: glutamate

Flashcard 2: What happens to the ornithine that is formed via the breakdown of arginine (urea cycle)? _____

Answer: It is recycled

Flashcard 3: Most disorders of the urea cycle require _____ as an essential amino acid, particularly during episodes of hyperammonemia

Answer: arginine

Flashcard 4: What enzyme converts Urea into Ammonia?_____

Answer: Urease

Flashcard 5: What is the most common urea cycle disorder? _____

Answer: Ornithine transcarbamylase (OTC) deficiency

Flashcard 6: When an amino acid is metabolized, it is broken down into a carbon skeleton and _____ (highly toxic)

Answer: NH3

Flashcard 7: Where does the urea cycle occur?

Answer: steps in both the cytoplasm and mitochondria

Flashcard 8: What is the rate-limiting enzyme of the Urea Cycle?

Answer: Carbamoyl phosphate synthetase I (CPS I)

Extra: CPS I is the rate-limiting enzyme of the urea cycle and is activated by N-acetylglutamate (NAG). It is located in the mitochondria.

Flashcard 9: What is the overall purpose of the urea cycle?

Answer: to get NH4+ from amino acid catabolism into an excretable form

Flashcard 10: What is the metabolic pathway and significance of Carbamoyl Phosphate Synthetase I (CPS I)?

Answer: Urea cycle (Rate-limiting step)

Extra: Activator: N-acetylglutamate (NAG) Location: Mitochondria Source of nitrogen: Ammonia (NH3)