Nitrogen 1 COPY Flashcards
What is the name given to nitrogen fixing bacteria?
Diazotrophs
What does the assimilation stage of the nitrogen cycle consist of?
Fixation (n2 to ammonium) TOGlutamate TOother amino acids TOProteins and other amino acids
What is the degradation stage of the nitrogen cycle?
Proteins/nucleotidesTOOther amino acidsTOGlutamateTONH4+
What is the effect of lightning on nitrogen gas?
Breaks the triple bond and makes NO(nitric oxide) or NO2 (nitrite)
What ways of fixing nitrogen exist?
Haber process, Lightning, Nitrogen fixing bacteria
Name two nitrogen fixing bacteria
Cyanobacteria and rhizobia
What do the nitrogen fixing bacteria require?
Lots of ATP, nitrogenase enzyme inhibited by oxygen - anaerobic conditions needed , cyanobacteria form heterocysts whose cell wall forms a wall to oxygen, leguminous plants contain legheomoglobin which binds to oxygen and provides an environment that nitrogenase can work.
What happens to ammonium once it is fixed?
Nitrifiction to nitrite (NO2-) to nitrate (NO3-) this is taken up by plants and microbes - then converted to ammonia via nitrile
What is special about glutamate?
It is the only amino acid that can directly obtain its nitrogen from NH4 and the only one that can give up its nitrogen directly
What are the 4 amino acids usually found in much higher concentrations than others?
Alanine, glutamine, glutamate and aspartate
How do organisms conserve N2?
Transamination - The transfer of amino groups from one biological molecule to another
What type of reaction is transamination if the reaction is reversible?
Synthesis and degradation
What do amino transferases rely on?
Pyridoxal phosphate cofactor transfers the amino acid during the reaction.
What molecule usually accepts the amino groups?
alpha ketoglutarate
Which molecule usually acts as a temporary storage of nitrogen?
L - Glutamine (possible of donating the amino acid when it is needed for biosynthesis)
What is pyridoxal phosphate made from?
Made from vitamin B6
What does presence of amino transferases in the plasma indicate?
Cell damage, as they are intracellular proteins
How much of a herbivores energy intake is met by amino acids?
Small fraction
Under which three circumstances do amino acids go under oxidative catabolism?
Leftover amino acids from normal protein turnoverExcess dietary amino acidsProteins in the body are broken down (during starvation)
How are dietary proteins enzymatically hydrolyzed?
Pepsin cuts proteins into peptides in the stomachPepsin and chymotrypsin cut proteins into smaller peptides in the small intestineAminopeptidase and carboxypeptidase degrade peptides in the small intestine to amino acids
Where can the aminopeptidases be found?
Intestine - membrane bound proteins
What is a carbon skeleton?
The leftovers of an amino acid
What is a ubiquinated protein?
Covalently modified protein to fit into the proteosome which is effectively a protein destroying machine.
What cellular proteins are degraded?
Misfolded proteins,Foreign proteinsUnwanted proteins
Eventually all proteins are …..
Turned over
Why do all excess amino acids have to be catabolised?
There is no storage facility for protein
