Nitrogen 1 Flashcards
What is nitrogen metabolism also known as?
Amino acid metabolism
What kinds of molecules contain nitrogen?
Amino acids and nucleotides
Where do we get our nitrogen from?
Our diet, not the air
What are the 2 stages of the nitrogen cycle in organmisms?
Assimilation
Degradation
Why is nitrogen very unreactive?
Nitrogen is bonded to another nitrogen with a triple bond
What are 3 things that supply the massive amound of energy required to breakdown nitrogen?
Lighting
450oC at 200atp with an iron catalyst
Bacteria
What does bacteria perform to breakdown nitrogen?
Nitrogen fixation
What does nitrogen fixation look like?
What is nitrogen inactivated by?
O2
How does bacteria get around O2 deactivating N2?
Live anaerobically
Uncouple mitochondria to burn all O2 in a cell
What does the process of nitrogen after it is fixed look like?
What does the flow of N2 from NH4+ to other biomolecules occur through?
Glutamate
How does glutamate pass on the nitrogen?
By interconverting into other molecules
What are the 4 amino acids in much higher concentrations in cells compared to others?
Alanine
Glutamine
Glutamate
Asparate
What do most organisms do because they cannot fix N2?
Conserve it by transamination
What is transamination?
Transfering amino group between diferent molecules
What does transamination look like?
What is the basic reaction formula of transamination?
Why is transamination involved in both the synthesis and degradation of nitrogen compounds?
The reactions of transamination are reversible
What do all amino transferases rely on?
The pyruidoxal phosphate cofactor
What is the typical molecule that accepts amino groups?
a-ketoglutamate
What does L-glutamate act as?
A temporary storage of nitrogen
What can L-glutamate do?
Donate amino groups when needed for amino acid biosynthesis
What is pyridoxal phosphate (PLP)?
Cofactor made from vitamin B6 (essential vitamin)
Transfers the amino group during the reaction
What does it mean if aminotransferases are found in the plasma?
There is tissue damage somewhere because aminotransferases are intracellular, this damage is usually in the liver
When do amino acids undergo oxidative catabolism?
Left over amino acids (from normal protein turnover)
Dietary amino acids
Proteins in the body (are broken down when carbohydrates are short)
What happens to dietary proteins?
They are enzymatically hydrolysed
What is the process of dietary proteins being enzymatically hydrolysed?
- Pepsin cuts protein into peptide in the stomach
- Trypsin and chymotrypsin cut proteins and large peptides into smaller peptides in the small intestine
- Aminopeptidase and carboxypeptidase A and B degrade peptides into amino acids in the small intestine
Why is the stomach acidic?
To help breakdown proteins
Where do the enzymes involved in the breakdown of dietary proteins come from?
Gastric glands in stomach lining
Exocrine cells in pancreas
Villi of small intestine
What cellular proteins would be targeted for destruction?
Misfolded proteins
Foreign proteins
Unwanted proteins
How are cellular proteins targeted for destruction?
Ubiquitin tags proteins that are to be degraded
What are the fates of amino acids from broken down proteins?
Left intact for biosynthesis
Broken down into amino groups and carbon skeleton, where the amino group is disposed of in the urea cycle
What are the 3 fates of carbon skeletons from broken down amino acids?
Glucose or glycogen synthesis
Cellular respiration
Fatty acid synthesis
