Nitrogen Metabolism Flashcards
Can you store nitrogen
no
name 3 things that nitrogen is an important component of
cofactors, hormones, neurotransmitters
can we use the N2 that is in the atmosphere
no, our atmosphere is made of 80% N , but it is in a non useful form.
what form of Nitrogen can we use?
NH3, ammonia
Does turning atmospheric nitrogen into ammonia have high or low activation energy ?
Very high activation energy
What are some processes to turn Nitrogen into a useful form?
2 non biological processes are:
N2 + o2 —> NO via lightening
N2+ H2 —-> NH3 via haber process
What are the oxidation states of nitrogen
-3 and +5
higher oxidation state is “ate” or “ite”
ate
lower oxidation state is ate or ite
lower is ite
what are the 4 steps in the nitrogen cycle ?
Fixation
Nitrofication
Assimilation
Denitrification
what does fixation refer to
bacteria reducing N2 —> NH3 (ammonia) or NH4 ( ammonium)
what does nitrification refer to ?
Bacteria oxidizing NH3—-> No2- ( nitride) and N03- (nitrate
What is assimilation
plants and microorgansims reducing NO2- and NO30 to NH3 via nitrite reductase and Nitrate reductase
what 2 enzymes are used in assimilation
nitrite reductase and Nitrate reductase
What does denitrification refer to
NO3- reduced to N2 under anaerobic conditions
what is the ultimate electron acceptor
NO3-
Do humans do nitrogen assimilation
no , only plants and bacteria have the ability to assimilate . Animals depend entirely on diet
how do plants assimilate nitrogen
the plants absorb the nitrogen from the soil in the form of Nitrate ( NO3-) and ammonia ( NH3)
In aerobic conditions do we see more nitrate or ammonia
nitrate predominates ( NO3-). Ammonia predominates in grasslands
what is the assimilated form of nitrogen for plants
ammonia
what are the 2 enzymes needed to convert nitrate into ammonia
nitrate reductase N03- + 2e—> NO2-
Nitrite Reductase NO2- +6e —> NH4+
What cofactor is required for nitrate reductase
Mo cofactor and NADH
What cofactor is required for nitrite reductase
siroheme . This is a heme like prosthetic group. It is synthesized from B12.
Do humans have the glutamine synthase enzyme or the glutamate synthase enzyme
we only have the glutamine synthase, no the glutamate synthase
what step is being described : the formation of organic nitrogen compounds like amino acids from inorganic nitrogen compounds present in the environment
nitrogen assimilation
can plants fungi and certain bacteria fix N2 gas
no , they depend on the ability to assimilate nitrogen for their needs
Do animals depend on organic or inorganic nitrogen from their food
organic
how is nitrogen transported from root to shoot in plants
nitrate is taken up by several nitrate transporters that use a proton gradient to power the transport
which pathway incorperates ammonia into amino acids
glutamine synthetase- glutamate synthase pathway
what is the electron donor in nitrate assimilation via nitrate reductase
NADH
Can all bacteria do nitrogen fixation
no , only certain archea and bacteria can fix atmospheric nitrogen . This special group of bacteria is called diazotrophs
what is the name of the special group of bacteria that can fix nitrogen
diazotrophs
name 3 kinds of diaztrophs that are capable of nitrogen fixation
Rhizobia, Frankia , Azospirillium
what is unique about diaztrophs that allow them to fix nitrogen
they have enzymes that allow them to overcome the high activation energy , by binding and hydrolating ATP
what is the important product of nitrogen fixation
ammonia
describe the nitrogenase complex
it is the complex that allows for nitrogen fixation by diazotrophs . The complex has 2 subunits : Dinitrogenase reductase and Dinitrogenase. 16 ATP are consumed .
what are the 2 subunits of the nitrogenase complex
dinitrogenase reductase and dinitrogenase
how many ATP are consumed in the the nitrogenase complex
16
What 2 cofactors are needed for the nitrogenase complex
iron molybedium and vanadium nitrogenase
what is one thing that nitrogen assimilation and and nitrogen fixation have in common
they are both electron transfer processes, both use a molybidium cofactor
is nitrogen fixation an aerobic or anaerobic process?
anerobic , because it is very unstable in the presence of oxygen . It only has a half life of 30 seconds in air !
what is leghmoglobin
It is an 02- binding heme. Many plants live in root nodules coated with this binding protein . This creates the anerobic environment that is needed for nitrogen fixation!
what is an annamox bacteria
they can take a short cut, no denitrification is needed
what does annamox refer to
anaerobic ammonia oxidation
an annamox bacteria can oxidize NH3 and NO2- into what
N2
what kind of bacteria are used in waste treatment for cheaper ammonia removal
annamox bacteria, because they can oxidize NH3 into NO2- and N2 .
ammonia is incorperated into biomolecules thru what to amino acids
glutamate and glutamine
ammonia enters organic linkages via what 3 reactions
- glutamine synthase
- Glutamate Dehydrogenase
- Carbomyl Phosphate Synthetase ( urea cycle)
glutamine (Gln) is made from glutamate ( Glu) by what enzyme
glutamine synthetase
how is glutamate generated
it is generated from alpha ketoglutarate via glutamate synthase
how is glutamine generated
from glutamate via glutamine synthetase
is glutamate synthase present in animals
no ! we generated glutamate via transamination
how do animals generate glutamate
through transamination which is catalyzed by aminotransferases
what cofactor is required by transamination
PLP
where does oxidative deaminaition occur
in the mitochondrial matrix
is ammonia toxic
yes , so it must be safely transported in the blood as glutamine
explain how excess ammonia in the tissues is transported
glutamine uses the enzyme glutamine synthase and turns it into glutamine
explain how excess ammonia in the liver is transported
glutamine uses the enzyme glutaminase to turn it into glutamine
where is the only place where glutaminase is found
in liver mitochondria
how is ammonia collected by glutamate removed
by glutamate dehydrogenase
in soil bacteria and plants ________ and _______ convert ___ to _____
nitrate reductase, nitrite reductase , NO3- , NH3
