nitrogen metabolism (deev- only one question) Flashcards
What is one of the most abundant porphyrin rings in the body?
Heme
____________ is most abundant but is too inert for use in most biochemical reactions.
Atmospheric nitrogen (N2)
True/False: Humans store nitrogen in the Liver.
False, we have no storage from of Nitrogen!
True/False: Nitrogen is a reactive compound.
True, most explosives contain nitrogen, so the body needs to get rid of any nitrogen that is above the needs.
Most nitrogen leaves the body via the _______ cycle.
Urea, clears body of excess nitrogen, but also retains carbon skeltons
How does nitrogen enter the body?
Most nitrogen enters in amino acids by digestion
What are 3 ways to input AAs?
Dietary protein (Digestion)
Protein turnover
amino acid synthesis de novo (from scratch)
What are 3 ways to output AAs?
Synthesis of proteins- Transcription, translation
Synthesis of other nitrogen containing compounds (nucleotides, heme)
Use of Carbon skeleton of AA for other compounds (i.e. glucose, lipids, ketone bodies) or for energy.
Input and output of AA is always balanced, why?
If you don’t have a certain amino acid in the body, certain proteins can’t be made…
What selectively degrade damaged or short-lived proteins, uses ubiquitin to target proteins for degradation? What energy does it use?
Proteasomes
Energy dependent mechanism—uses ATP
What non-selectively degrades intracellular proteins (autophagy) and extracellular (heterophagy)?
Lysosomes
use acid hydrolases to brake down peptide bonds to short peptides and AA
Enzyme in stomach?
Pepsin
Small intestine enzymes?
Pancreatic enzymes- trypsin, chymotrypsin, elastase, Carboxypeptidase
Aminopeptidases, Di- and Tripeptidases
All enzymes cleave specific sequences of amino acids via 2 enzymes.
Endopeptidases - inside a peptide sequence
Exopeptidases- from the ends (exo) of a peptide sequence
Peptides are hydrolyzed to amino acids in the ______.
Cytosol
Only free amino acids are found in the ________ after a meal containing protein.
portal vein
Branched chain amino acids are not metabolized by the liver, instead sent from liver primarily to _____ via blood.
Muscle
What is the first step and what enzymes are involved in the removal of Nitrogen from Amino Acids? What is the name of the step?
Step 1: Transamination, aminotransferase
transfers AA to alpha ketogluterate producing alpha keto acid.
What is the 2nd step and what enzymes are involved in the removal of nitrogen from amino acids? Where does this occur?
Step 2: Oxidative deamination, Glutamate dehydrogenase
Occur in Liver and Kidney
What are the sources of ammonia?
Dietary AA Glutamine Bacterial action Amines Catabolism of purines and pyrimidines
Ammonia is constantly produced in the ________ but is present at very low levels in blood.
tissues
_________ is highly neurotoxic and must be kept at low levels in the blood
Ammonia
Any free ammonia present in the circulation will be removed by the ______, and used for synthesis of ___.
Liver
Urea
Free ammonia is released in the _____ and contributes to the acid-base balance of the body by excreting protons.
urine
What is a general term for elevated levels of ammonia in the blood, which can be due to many different conditions.
Hyperammonemia
Elevated ______, above 1000 micromol/l, ________ intoxication is a medical emergency and can have effects on the CNS/ blurring of vision
ammonia
ammonia
A disease that is due to a deficiency in cystathionine synthase. Promotes damaging of LDLs and dislocation of the lens can occur.
Homocystinuria in the urine
A defect in enzymes involved in the conversion of tyrosine to melanin will cause _______.
Albinism
Most severe form of albinism is the deficiency in the enzyme ______ and results in a complete lack of pigment.
tyrosinase
