Nitrogen Flashcards
Nitrogen fixing requires
nitrogenase
lots of energy
nitrogenase is inactivated by
oxygen
Leguminous plants produce leghemoglobin which binds O2 allowing the concentration to be…
low enough to allow nitrogenase to work
nitrogen fixation produces
ammonia
once ammonia is fixed it is converted into ……..
a usable form of nitrogen taken up by plants and microbes
nitrate
Flow of nitrogen from ammonia to other biomolecules occurs through
glutamate
eg Urea
Transamination
transferring amino groups between different molecules
in order to conserve nitrogen
a chemical reaction that transfers an amino group to a ketoacid to form new amino acids.
transamination
aminotransferases
intracellular enzymes
glutamate can only ‘lose’ nitrogen by
transamination
Humans excrete nitrogen as
urea and uric acid
Ammonia is transported in the bloodstream safely as
glutamate
Glutamate can donate ammonia to ………. to make …………
pyruvate
alanine
(or can be made into glutamine)
Glycolysis yields
pyruvate
if not eliminated LACTIC ACID will build up
excess pyruvate can be converted to………. for transport to the
alanine
liver
what charge does glutamate have?
negative
-ve
what charge do alanine and glutamine have?
no charge
charged molecules don’t pass through membranes so easy - they have to be converted to
uncharged molecules
Catabolism of amino acids involves transfer of the amino group via PLP-dependent aminotransferase to a donor such as………. to yield
alpha-ketoglutarate
glutamine
toxic ammonia is quickly recaptured into carbamoyl phosphate and passed into
the urea cycle
L-glutamine can be used to create new …………. or it can dispose of……..
amino acids
excess nitrogen via ammonia
Most inherited metabolic disorders are
autosomal recessive inheritance
there are ….. inherited disorders of the urea cycle
6
urea cycle defects are most common in ………………… deficiency
ornithine transcarbamoylase (OTC)
OTC has …………. inheritance
x - linked
Phenylketonuria
absence of phenylalanine hydroxylase (PAH)
increased phenylalanine levels
Phenylketonuria treatment
low protein diet supplemented with protein substitute
