Nitrogen Metabolism Flashcards
What is the immediate precursor of organic forms of nitrogen?
Ammonia
What are the initial organic forms of nitrogen?
Glutamate, glutamine, and carbamoyl phosphate
Where are the most abundant sources of nitrogen found?
Nitrites and nitrates in the soil and N2 gas in the atmosphere
What are the essential amino acids?
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
What molecules are made from tryptophan?
Melatonin
Serotonin
Niacin
Auxins
How are amino acids catabolized?
Dietary protein catabolism
Endogenous protein degradation
What is ubiquitination?
Targetting of proteins for degradation by proteosome
What happens when there are sufficient amino acids?
Synthesis in inhibited and excess are converted to energy storage molecules.
What does alpha-KG do?
Makes other amino acids.
Where does the urea cycle occur?
Liver
What enters and exits the urea cycle?
2 nitrogens enter on carbamoyl phosphate and on aspartate and leave as urea
When are amino acids ketogenic?
When the R group enters as acetyl-CoA
When are amino acids glucogenic?
When the R group enters elsewhere
Where is insulin released and what does insulin do?
Pancreas; stimulates fuel storage and inhibits gluconeogenesis
