UREA CYCLE Flashcards
fuel is formed from ammonium ion (from oxidative deamination), carbon dioxide (from the citric acid cycle), water, and two ATP molecules
Carbamoyl Phosphate
a cyclic biochemical pathway in which urea is produced, for excretion, using ammonium ions and aspartate molecules as nitrogen sources
urea cycle
first molecule of “fuel”
entering the cycle
Citrulline
transported in the blood to the kidneys and eliminated from the body in urine
urea
second molecule of “fuel” entering the cycle
Aspartate
Three amino acids are involved as intermediates in the operation of the urea cycle
arginine
ornithine
citrulline
Citrulline–aspartate condensation enzyme
argininosuccinate synthase
an adult excretes about __ g of urea daily in urine
30
Hydrolysis of arginine produces urea and regenerates ornithine, one of the cycle’s starting materials
Step 4: Urea from arginine hydrolysis.
“fuel” for the urea cycle
Carbamoyl Phosphate
amino acid that has a carbon-containing product that can be used to produce glucose via gluconeogenesis
Glucogenic amino acid
enzyme involved in Step 4: Urea from arginine hydrolysis
arginase
Amino acids that are degraded to acetyl CoA or acetoacetyl CoA can contribute to the formation of fatty acids or ketone
bodies
ketogenic
formed via the urea cycle is excreted in urine
urea
an amino acid that has a carbon-containing degradation
product that can be used to produce ketone bodies
ketogenic amino acid