Nitrogen Economy 2 Flashcards
Pyruvate can be converted into _____, which can carry both pyruvate and ____ into the liver
Converted into alanine, and alanine can carry both pyruvate and ammonia
Glucose in the muscle produces ___ through glycolysis. ___ can then undergo gluconeogenesis in the liver to produce glucose for export to muscle
Pyruvate
Gluconeogenesis is controlled by two hormones:
Glucagon and Cortisol
The two sources of nitrogen that act as fuel in urea are:
Ammonia and aspartate
What happens in an aminotransferase reaction?
An amino acid transfers its amino group to a keto- group, making it an amino group. The previous amino acid then becomes a keto- group.
Describe alanine aminotransferase / transaminase
Alanine transfers its amino group to alpha-ketoglutarate. Alanine becomes pyruvate, A-k becomes glutamate
Describe aspartate transaminase / aminotransferase
Aspartate transfers amino group to alpha-ketoglutarate. Asp become OAA, A-k becomes glutamate
Glutamine or alanine: which of these two AAs are carrying the higher load of ammonia?
Glutamine (has 2 molecules of ammonia)
What is the enzyme used, to reversibly convert glutamate into A-k and ammonia?
Glutamate dehydrogenase. This enzyme is also used to make glutamate from ammonia and A-k (reversible)
What are the positive and negative modulators of glutamate DH?
Positive: ADP (liver) and leucine (pancreas)
Negative: GTP
Where is glutamine produced, via glutamine synthetase? (muscle, brain or liver)
Produced in the muscle, unpacked in the liver.
FYI: In the muscle, glutamate and ammonia, via glutamate synthetase, is converted to glutamine, which then goes to the liver
The, the glutamine is unpacked by glutaminase into glutamate and ammonia. The glucose-alanine cycle can then start
What are the branched-chain AAs are oxidized and processed by the muscle?
Valine, leucine, isoleucine. The liver does not process these.
How does the kidney assist in metabolic acidosis?
Liver slows down use of glutamine by downregulating glu transporters. The now-excess amount of glutamine in the blood goes to the kidney. Kidney uses the glu to cope with metabolic acidosis and to also produce the glucose that was not produced by the liver
Metabolic acidosis, caused by excess amounts of ketone bodies, is due to:
excess degradation of beta-oxidation of fatty acids
