Nitrogen sources and transport forms — Flashcards

Flashcard 1: Hyperammonemia results in excess NH3, which depletes _____, leading to inhibition of the TCA cycle

Answer: α-ketoglutarate

Flashcard 2: What is the major transport form of NH3 in the blood (from most tissues)? _____

Answer: Glutamine

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

Answer: arginine

Flashcard 4: Which tissue/organ uses alanine as its major transport form of NH3? _____

Answer: Muscle

Flashcard 5: The NH3 in the intestine may be transported to the liver in the form of _____ in the portal blood

Answer: NH3

Flashcard 6: What class of enzymes is used in the transfer of amino groups during nitrogen metabolism?

Answer: Aminotransferases (Transaminases)

Flashcard 7: When an amino acid is metabolized, it is broken down into a carbon skeleton and _____ (highly toxic)

Answer: NH3

Flashcard 8: Where does the urea cycle occur?

Answer: steps in both the cytoplasm and mitochondria

Flashcard 9: 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 10: What is the overall purpose of the urea cycle?

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