Nitrogen Metabolism

Question 1

Can you store nitrogen

Answer 1

no

Question 2

name 3 things that nitrogen is an important component of

Answer 2

cofactors, hormones, neurotransmitters

Question 3

can we use the N2 that is in the atmosphere

Answer 3

no, our atmosphere is made of 80% N , but it is in a non useful form.

Question 4

what form of Nitrogen can we use?

Answer 4

NH3, ammonia

Question 5

Does turning atmospheric nitrogen into ammonia have high or low activation energy ?

Answer 5

Very high activation energy

Question 6

What are some processes to turn Nitrogen into a useful form?

Answer 6

2 non biological processes are:

N2 + o2 —> NO via lightening
N2+ H2 —-> NH3 via haber process

Question 7

What are the oxidation states of nitrogen

Answer 7

-3 and +5

Question 8

higher oxidation state is “ate” or “ite”

Answer 8

ate

Question 9

lower oxidation state is ate or ite

Answer 9

lower is ite

Question 10

what are the 4 steps in the nitrogen cycle ?

Answer 10

Fixation
Nitrofication
Assimilation
Denitrification

Question 11

what does fixation refer to

Answer 11

bacteria reducing N2 —> NH3 (ammonia) or NH4 ( ammonium)

Question 12

what does nitrification refer to ?

Answer 12

Bacteria oxidizing NH3—-> No2- ( nitride) and N03- (nitrate

Question 13

What is assimilation

Answer 13

plants and microorgansims reducing NO2- and NO30 to NH3 via nitrite reductase and Nitrate reductase

Question 14

what 2 enzymes are used in assimilation

Answer 14

nitrite reductase and Nitrate reductase

Question 15

What does denitrification refer to

Answer 15

NO3- reduced to N2 under anaerobic conditions

Question 16

what is the ultimate electron acceptor

Answer 16

NO3-

Question 17

Do humans do nitrogen assimilation

Answer 17

no , only plants and bacteria have the ability to assimilate . Animals depend entirely on diet

Question 18

how do plants assimilate nitrogen

Answer 18

the plants absorb the nitrogen from the soil in the form of Nitrate ( NO3-) and ammonia ( NH3)

Question 19

In aerobic conditions do we see more nitrate or ammonia

Answer 19

nitrate predominates ( NO3-). Ammonia predominates in grasslands

Question 20

what is the assimilated form of nitrogen for plants

Answer 20

ammonia

Question 21

what are the 2 enzymes needed to convert nitrate into ammonia

Answer 21

nitrate reductase N03- + 2e—> NO2-

Nitrite Reductase NO2- +6e —> NH4+

Question 22

What cofactor is required for nitrate reductase

Answer 22

Mo cofactor and NADH

Question 23

What cofactor is required for nitrite reductase

Answer 23

siroheme . This is a heme like prosthetic group. It is synthesized from B12.

Question 24

Do humans have the glutamine synthase enzyme or the glutamate synthase enzyme

Answer 24

we only have the glutamine synthase, no the glutamate synthase

Question 25

what step is being described : the formation of organic nitrogen compounds like amino acids from inorganic nitrogen compounds present in the environment

Answer 25

nitrogen assimilation

Question 26

can plants fungi and certain bacteria fix N2 gas

Answer 26

no , they depend on the ability to assimilate nitrogen for their needs

Question 27

Do animals depend on organic or inorganic nitrogen from their food

Answer 27

organic

Question 28

how is nitrogen transported from root to shoot in plants

Answer 28

nitrate is taken up by several nitrate transporters that use a proton gradient to power the transport

Question 29

which pathway incorperates ammonia into amino acids

Answer 29

glutamine synthetase- glutamate synthase pathway

Question 30

what is the electron donor in nitrate assimilation via nitrate reductase

Answer 30

NADH

Question 31

Can all bacteria do nitrogen fixation

Answer 31

no , only certain archea and bacteria can fix atmospheric nitrogen . This special group of bacteria is called diazotrophs

Question 32

what is the name of the special group of bacteria that can fix nitrogen

Answer 32

diazotrophs

Question 33

name 3 kinds of diaztrophs that are capable of nitrogen fixation

Answer 33

Rhizobia, Frankia , Azospirillium

Question 34

what is unique about diaztrophs that allow them to fix nitrogen

Answer 34

they have enzymes that allow them to overcome the high activation energy , by binding and hydrolating ATP

Question 35

what is the important product of nitrogen fixation

Answer 35

ammonia

Question 36

describe the nitrogenase complex

Answer 36

it is the complex that allows for nitrogen fixation by diazotrophs . The complex has 2 subunits : Dinitrogenase reductase and Dinitrogenase. 16 ATP are consumed .

Question 37

what are the 2 subunits of the nitrogenase complex

Answer 37

dinitrogenase reductase and dinitrogenase

Question 38

how many ATP are consumed in the the nitrogenase complex

Answer 38

16

Question 39

What 2 cofactors are needed for the nitrogenase complex

Answer 39

iron molybedium and vanadium nitrogenase

Question 40

what is one thing that nitrogen assimilation and and nitrogen fixation have in common

Answer 40

they are both electron transfer processes, both use a molybidium cofactor

Question 41

is nitrogen fixation an aerobic or anaerobic process?

Answer 41

anerobic , because it is very unstable in the presence of oxygen . It only has a half life of 30 seconds in air !

Question 42

what is leghmoglobin

Answer 42

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!

Question 43

what is an annamox bacteria

Answer 43

they can take a short cut, no denitrification is needed

Question 44

what does annamox refer to

Answer 44

anaerobic ammonia oxidation

Question 45

an annamox bacteria can oxidize NH3 and NO2- into what

Answer 45

N2

Question 46

what kind of bacteria are used in waste treatment for cheaper ammonia removal

Answer 46

annamox bacteria, because they can oxidize NH3 into NO2- and N2 .

Question 47

ammonia is incorperated into biomolecules thru what to amino acids

Answer 47

glutamate and glutamine

Question 48

ammonia enters organic linkages via what 3 reactions

Answer 48

1. glutamine synthase 2. Glutamate Dehydrogenase 3. Carbomyl Phosphate Synthetase ( urea cycle)

Question 49

glutamine (Gln) is made from glutamate ( Glu) by what enzyme

Answer 49

glutamine synthetase

Question 50

how is glutamate generated

Answer 50

it is generated from alpha ketoglutarate via glutamate synthase

Question 51

how is glutamine generated

Answer 51

from glutamate via glutamine synthetase

Question 52

is glutamate synthase present in animals

Answer 52

no ! we generated glutamate via transamination

Question 53

how do animals generate glutamate

Answer 53

through transamination which is catalyzed by aminotransferases

Question 54

what cofactor is required by transamination

Answer 54

PLP

Question 55

where does oxidative deaminaition occur

Answer 55

in the mitochondrial matrix

Question 56

is ammonia toxic

Answer 56

yes , so it must be safely transported in the blood as glutamine

Question 57

explain how excess ammonia in the tissues is transported

Answer 57

glutamine uses the enzyme glutamine synthase and turns it into glutamine

Question 58

explain how excess ammonia in the liver is transported

Answer 58

glutamine uses the enzyme glutaminase to turn it into glutamine

Question 59

where is the only place where glutaminase is found

Answer 59

in liver mitochondria

Question 60

how is ammonia collected by glutamate removed

Answer 60

by glutamate dehydrogenase

Question 61

in soil bacteria and plants ________ and _______ convert ___ to _____

Answer 61

nitrate reductase, nitrite reductase , NO3- , NH3