Ammonia Metabolism Flashcards
NH4+ cannot cross membranes easily while NH3 can. (T/F)
T
Where do AA first go when transported into the blood after digestion?
The Liver
What type of pump drives AA into the cell from the lumen of the intestine?
An Na+ pump. (Secondary active transport)
Name the the compound of these species after deamination. Also, what are their functions?
Glutamate
Aspartate
Alanine
Glutamine
a-ketoglutarate The amino group pool of the cell
oxaloacetate Donates nitrogen to the urea cycle
pyruvate A key role in gluconeogenesis
glutamate Transports nitrogen to liver for urea cycle
Glucagon, cortisol, epinephrine and norepinephrine all [ ] mobilization of stored fuels.
promote
What are two key AA that leave cell when fasting?
Glutamine and Alanine
alpha-ketoglutarate (a-KG) acts as the universally accepts what?
amine groups
What does alanine get broken down into while in the fasted state? Where does this take place?
Glucose (which goes back to muscle) and Urea.
The liver.
Glutamate dehydrogenase and glutamine synthase can add free ammonium to “fix” it as glutamine. These reactions require energy. (T/F)
T
Which AA activates the production of NAG which then activate CPSI in the Urea Cycle.
Arginine
Name two broad conditions where the urea cycle would function on a high level.
Starvation and a high protein diet.
High NH4+ levels in the blood point to a problem with:
The Urea Cycle
Elevated urinary oratic acid suggests what?
A mutation close to carbamoyl phosphate
In the Urea Cycle, if the the ornithine / citrulline antiporter is defective, what condition would you associate with this defect?
HHH, (hyperammonaemia, hyperornithaemia, homocitrullinaemia)
N-carbamoylglutamic acid lowers NH4+ levels so it deactivates CPSI (T/F)
F, it does lower NH4+ levels, but it activates CPSI. (It replaces NAG if NAG is deficient)
