Nitrogen Metabolism

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Diazetrophs

Back 1

Nitrogen fixing organisms that colonize root nodules leguminous plants

Front 2

N2 reduction requires a lot of (?) and strong (?) like ferredoxin to (?)

Back 2

ATP
Strong reducing agents
Electrons

Front 3

Net reaction for N2 reduction

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N2 + 8H + 8e- + 16ATP + 16H20 --> 2NH3 + H2 + 16ADP + 16Pi

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(?)e- needed for nitrogenase reaction, but only (?) needed for formal nitrogen reduction. The remaining electrons are used to produce (?)

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8
6
H2

Front 5

Takes about (?) ATP per N2 reduced

Back 5

20-30

Front 6

What inactivates nitrogenase?

Back 6

Oxygen

Front 7

NO3- (Name?) is found in water and soils and is reduced by plants/fungi/bacteria

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Nitrate

Front 8

NO2-

Back 8

Nitrite

Front 9

Ammonia exists in protonated form as (?) and has a pK of (?)

Back 9

NH4+
9.25

Front 10

Nitrificaton

Back 10

Production of nitrate by bacteria that oxidize NH4+ to NO2- to No3-

Front 11

Nitrogen is assimilated into an (?) to produce Glu

Back 11

Citric acid intermediate

Front 12

What is deanimated to produce a second Glu?

Back 12

Gln (Glutamine

Front 13

Glutamine synthetase does what in bacteria/mammals?

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Bacteria: Metabolic entry point for fixed nitrogen

Animals: Mop up excess ammonia

Front 14

Mammals produce glutamate via

Back 14

Glutamate dehydrogenase

Front 15

Glutamine synthetase reaction that introduces ammonia into biological compounds requires substrate called

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Glutamate

Front 16

What is the source of nitrogen in bacteria/plants?

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Enzyme glutamate synthase

Front 17

Transamination

Back 17

Amino groups transferred from molecule to molecule with glutamate as amino group donor

Front 18

A transaminase catalyzes transfer of what to what?

Back 18

Amino group to alpha-keto acid

Front 19

Transaminase example:

Glutamate + What <--> What + What?

Back 19

Glutamate + Pyruvate (alpha keto acid) <--> alpha-ketogluterate + Alanine

Front 20

Most transaminases generate

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Glutamate or aspartate

Front 21

What is the only AA that can't be transaminated?

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Lysine

Front 22

Tyr is produced from _____ via what? By what enzyme?

Back 22

Phe via hydroxylation...through phenylalanine hydroxylase

Front 23

Aspartate --> Asparagine via what enzyme

Back 23

Asparagine synthetase

Front 24

Three common metabolic intermediates?

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Pyruvate
Oxaloacetate
alpha-ketoglutarate

Front 25

Glutamate can be converted to what and what?

Back 25

Proline and Arginine

Front 26

Serine can be derived from glycolytic intermediate ?

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3-phosphoglycerate

Front 27

Serine gives rise to what?

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Glycine

Front 28

Tetrahydrofolate?

Back 28

Carrier of one-carbon units in several nitrogen rections

Front 29

Deficiency in folate results in?

Back 29

Neural tube defects like spina bifida

Front 30

Pyruvate -->
Oxaloacetate -->
alpha-ketoglutarate -->

Back 30

Alanine
Aspartate
Glutamate

Front 31

Sulfur containing amino acids begin with

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Serine + sulfur from inorganic sulfide

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Synthesis of methionine

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Serine --> Cysteine --> Homocysteine --> Methionine

IN PLANTS

Front 33

In humans, serine reacts with what to produce cysteine?

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Homocysteine

Front 34

GABA?

Back 34

y-aminobutryic acid

Front 35

Tyrosine gives rise to what three compunds? And what are these called?

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Dopamine, norepinephrine, and epinephrine. Called catecholamines (resemble catechol)

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Front 37

Tryptophan leads to ?

Back 37

Serotonin

Front 38

Degradation of carbon skeletons of ____ produces ____ and precursors for _____

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Amino acids
Acetyl-CoA
Gluconeogensis

Front 39

Glucogenic means

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Giving rise to gluconeogenic precursors --> Glucose

Front 40

Ketogenic means

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Give rise to acetyl-CoA

Front 41

Catabolism of AA does not proceed all the way to ?

Back 41

CO2

Front 42

Ketogenic AA

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Leucine
Lysine

Front 43

Both ketogenic and glucogenic

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Isoleucine
Phenylalanine
Threonine
Tryptophan
Tyrosine

Front 44

Ketone bodies are made of ? and are synthesized in ?

Back 44

Acetoacetate + beta-hydroxybutyrate

Liver mitochondria

Front 45

Acetoacetate can go to what two things?

Back 45

3-hydroxybutyrate and acetone

Front 46

Ammonia released by ? is concorporated into ?

Back 46

Glutamate dehydrogenase
Carbamoyl phosphate

Front 47

Starting substrate for urea cycle is produced by ?

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Carbomyl phoshate synthetase

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Front 51

Urea production is controlled by

Back 51

Carbomyl phosphate synthetase

Front 52

When amino acids are being catabolized, increased ? and ? increase production of ?

Back 52

Glu and acetyl-Coa

N-acetylglutamate