Nitrogen metabolism 1

Created by: TaraCBeckworth
Created on: 26-08-18 19:47

What is nitrogen fixation?

Biological conversion of atmospheric nitrogen to ammonia (Only carried out in certain bacteria and algae) E.g. rhizobium in legume root nodules

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Describe the nitrogenase complex

A 2 enzyme complex that reduces nitrogen, 2 components (Nitrogenase and nitrogenase reductase), reaction requires ~16ATP and also the reducing power of ferredoxin

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Nitrogenase reductase

(Component 2) Fe-protein, small molecule (4 Fe and 4 S atoms/ molecule), 1 or 2 nitrogenase reductase molecules in a nitrogenase complex, reduced by accepting electrons from ferredoxin, re-oxidised when it passes e's to nitrogenase

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Nitrogenase

Large protein made up of several subunits, reduced by accepting electrons from nitrogenase reductase and is re-oxidised when they are transferred to N2 and H+ to form ammonia

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What is ammonia assimilation?

The incorporation of inorganic nitrogen into organic nitrogen

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What are the 2 routes by which assimilation can take place?

Glutamate dehydrogenase (GDH) and Glutamine synthase (GS)

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Glutamate dehydrogenase

No requirement for ATP, low affinity for NH3, meaning it is almost inactive when NH3 is low, most energetically efficient (most efficient at high NH3 levels)

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Glutamine synthase

Requires ATP, high affinity for NH3, meaning when NH3 is low, it has high activity (Least energetically efficient and most efficient at low NH3 levels

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What is the formula for the GDH reaction?

2-oxo-glutarate + NAHPH+H +NH3 ----> Glutamate + NADP+ +H2O

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What is the formula for the GS reaction?

Glutamate + ATP + NH3 ---> ADP+Pi + Glutamine

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Other cards in this set

Card 2

Front

Describe the nitrogenase complex

Back

A 2 enzyme complex that reduces nitrogen, 2 components (Nitrogenase and nitrogenase reductase), reaction requires ~16ATP and also the reducing power of ferredoxin

Card 3

Front

Nitrogenase reductase

Back

Card 4

Front

Nitrogenase

Back

Card 5

Front

What is ammonia assimilation?

Back

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Nitrogen metabolism 1