Nitrogen Flashcards
How do nitrogen fixing bacteria live
anerobically
what inactivates nitrogen fixing bacteria
oxygen
what do root nodules on legumes contain
Rhizobium bacteria
example of nitrogen fixing bacteria
cyanobacteria
Why are leguminous plants important for nitrogenous activity
legheamoglobin combines to oxygen making conditions aerobic therefore nitrogenase can work
Nitrogen fixing requires
nitrogenase enzyme and a lot of ATP
cyanobacteria forms what to prevent oxygen entry
heterocysts
example of symbiotic relationship
Leguminous plants and nitrogenase
what usable form of nitrogen is taken up by plants
Nitrate
Flow of N from NH4+ to other biomolecules occurs through
glutamate
Glutamate formed by
ketoglutarate and ammonia
what 4 amino acids are held in much higher concentrations
Alanine, glutamine, glutamate and aspartate
organisms can fix N2 therefore conserve nitrogen by
Transaminations
Whats is transamination
transfer of amino groups between different molecules
Taking an amino acid of creates a
ketoacid
In transamination one of the two substrates always has to be
glutamate
the synthesis and degradation of amnio acids is
reversible
what typically accepts amino groups
α-ketoglutarate
The enzyme catalysing transamination is
aminotransferases
aminotransferases depends on cofactor
pyridoxal phosphate
what acts as temporary storage for nitrogen
L glutamine
pyridoxal phosphate derive from
vitamin b6
If aminotransferase present in plasma indicates
cell damage i.e. liver disease
structure of amino acid
NH3 group attached to a carbon which is attached to a COOH
structure of a ketoacid
a C double bond O attached to the COOH group
amino acid biosynthesis
addition of amino groups to the carbon skeletons of a-keto acids
example of a ketoacid
pyruvate
Amino acids undergo oxidative catabolism under three circumstances
Left over proteins, degraded
Dietary proteins exceed protein synthesis
Starvation, proteins broken down
Whats happens to dietary proteins
enzymatically hydrolysed
What enzymes breaks down proteins in the stomach
pepsin
trypsin and chymotrypsin cut proteins into further peptides in the
small intestine
what does amniopeptidase do to proteins crossing over into in intestine
degrade proteins into amnio acids
What can also be targeted for destruction and has same endpoint as dietary proteins
cellualr proteins
what pathway is used to digest dietary proteins to amino acids
anabolic (storage energy)
What happens to proteins that are ingested exceeding body’s needs
Have to be catabolised as no storage facility
what does glycolysis yield
pyruvate
what it it pyruvate transformed into for transport
alanine
What is gout
build up uric acid crystallising in the joints
causes of gout
high protein diet
where is excess glutaine transported
intestines, kidneys and liver
Glutamnine is transformed into alanine for transport of amino group as
alanine has 0 charge so can diffuse across membrane easily compared to glutamines -ve charge
what does glutamine add on to alanine
amino group
what two reactions happen in Glutamate Dehydrogenase Reaction
Two-electron oxidation of glutamate followed by hydrolysis
where does glutamate dehydrogenase occur
mitochondria
what is the electron acceptor in glutamate dehydrogenase
NAD
Glutamate is broken down into
NH4 and ketoglutarate
NH4 is synthesised into what
Carbamoyl Phosphate
Carbamoyl Phosphate sythetase enzyme requires
Bicarbonate
ATP
Ammonia is recaptured by carbamoyl phosphate in the
mitochondria
The carbon skeleton of glutamate is
ketoglutarate
what is the first nitrogen to enter urea cycle
carbonyl phosphate
Where do products of glutamate dehydrogenase go
Urea cycle
what is ketoglurate amino group transferred to
asparate
what is the second nitrogen to enter urea cycle
asparate
where does urea cycle occur
cytosol
what happens to cytoskeleton after removal of amino group
converted to glucose or oxidised as part of the citric acid cycle
Carbon atoms of degraded amino acids become
metabolic intermediates
Name the 6 metabolic intermediates
acetly coA pyruvate oxoacetate ketoglutarate Fumarate succinyl-CoA
where is fumarate produced
from urea cycle
Metabolic intermediates are
glucogenic or ketogenic
metabolic intermediates are found in which cycle
citric
what amino acids are with either ketogenic or glycogenic
isoleucine, tyrosine and phenylalanine
what metabolic intermediates are not glycogenic
acetyl coA and acetoacetate
glucogenesis
glucose produced from non carbohydrate substates
why can’t acetyl coA go through glucogenesis
as acetyl coA can not be reconverted to pyruvate therefore can produced glucose
what is produced in ketogeneisis
ketone bodies
where are ketone bodies produced
Liver
What doesn’t use ketone bodies
liver
where are ketone bodies transported
liver to tissue
How do ketone bodies fuel the body
reconverted to acetly coA and go through citric cycle
Properties of ketone bodies
small, and water soluble
what can L glutamine do
synthesize new amino acids, or it can dispose of excess nitrogen as ammonia
what catches toxic ammonia
carbonyl phospahte
Carbon skeletons of amnio acids are
broken down to give energy
what is inherited metabolic disorders usually due to
single gene defect
inherited metabolic diseases usually result in abnormal synthesis of
Proteins
Amino acids
Carbohydrate
Lipids
effects of enzyme defects
Decreased formation of the product
Accumulation of the substrate
Increased formation of other metabolites
Heterozygotes of inherited metabolic disorders are usually
phenotypically normal
disorder of urea cycle usually occurs on what enzyme
transcarbamoylase
Failure of transcarbamoylase in urea cycle results in
elevated ammonia levels (hyperammonaemia)
transcarbamoylase synthesises
carbamyl phosphate into citrulline
Treatments of transcarbamoylase defect to reduce ammonia levels
introduction of aginine, Sodium phenylbutyrate, and Sodium benzoate, allows urea to be produced
Amino acids disorder results in
Decreased product
Increased precursors
Alternative metabolic products
example of amino acid disorder
Phenylketonuria (PKU)
what causes PKU
absence of Phenylalanine hydroxylase enzyme, therefore increased levels of Phenylalanine
PKU causes
impaired brain development
What disorder is PKU
autosomal recessive
Diagnosis of PKU
decreased levels of tyrosine
Treatment of PKU
low protein diet i.e. with supplement
