week 3 nitrogen Flashcards
do carbohydrates and fats contain nitrogen
no
do amino acids and nucleotides contain nitrogen
yes
what are the main nitrogen-containing molecules in the body
amino acids and nucleotides
where do we get nitrogen from
our diet (not air!!!)
how are dietary proteins enzymatically hydrolysed
- pepsin cuts protein into peptides in the stomach
- trypsin and chymotrypsin cut proteins and larger peptides into smaller peptides in the small intestine
- aminopeptidase and carboxypeptidases A and B degrade peptides into amino acids in the small intestine
what is enzymatic degradation of dietary proteins
dietary proteins being degraded to form amino acids
where do you get enzymatic degradation of dietary proteins
- gastric glands in stomach lining
- exocrine cells of pancreas
- villi of small intestine
how many essential amino acids
9
histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine
- these cannot be made in the body so we have to get them from diet
why can cellular proteins sometimes be targeted for destruction
sometimes misfolded proteins, foreign proteins and unwanted proteins are degraded for their amino acids
what does the urea cycle do
takes ammonia and turns it into urea
how do we get ammonia in the body
amino acid metabolism results in the formation of ammonia
- if ammonia is present in too high a concentration it is toxic so this is why it is turned into urea (in the liver) which isn’t very toxic and can be excreted in urine
how is nitrogen transferred to, from and between amino acids
by oxidative deamination and transamination (aminotransfer) reactions involving glutamate.
what is special about glutamate
only amino- acid that can obtain its nitrogen directly from ammonium ions.
how is nitrogen transported through plasma to liver
as glutamine
how is nitrogen transported from skeletal muscle
as alanine
