Nitrogen Metabolism

Nitrogen alters its _____ state in the nitrogen cycle

redox

Atmosphere or molecular nitrogen is _____

N2

All biological compounds contain N in its most ____ form, with an oxidation state of ____

reduced, -3

Nitrogen gas is very ______, making it unavailble to biochemical processes, due to its _____ bond making it hard to break

unreactive, triple

Nitrogen fixation is when _____ is converted to _______

molecular nitrogen (N2), another form

Denitrification is when ____ is converted to its ______, and escapes into the atmosphere

available nitrogen, molecular form

The natural process of nitrogen fixation, _______ nitrogen fixation, involves lightning and oxidizes N2 by _____, which is then hydrated by water and will precipitate to surface

atmospheric, O2

The industrial nitrogen fixation process, _______ process, uses ____ gas to reduce N2 and form ammonia.

Haber-Bosch, H2

The biochemical nitrogen fixation process involves _______________, and converts N2 to fully reduced _____ using ______ as an energy source.

nitrogen-fixing bacteria, NH3/NH4+, ATP

All organisms that use biological nitrogen fixation use the enzyme _____ and require a _____-free environment

nitrogenase, O2

There is a _______ between legumes and Rhizobia (bacteria), where bacteria in the root nodules provides reduced _______ and the plant provides reduced ______

symbiotic, nitrogen, carbon

The plant transport O2 away from the nodules using the transport protien ______ for the O2 free environment necessary for operation

leghemoglobin

The nitrogenase complex is made up of two enzymes:
1.___________
2.__________

nitrogen reductase, nitrogenase

The net result of the nitrogenase complex is the conversion of _______ to an _______

atmospheric nitrogen, ammonium ion

There is _____ ATP consumed per N2 reduced in the nitrogenase complex

16

A total of ___ electrons are transferred in the nitrogenase complex

8

THe reaction rate of the nitrogenase complex is very ____, with just _____ molecules of N2 per second

slow, 3

The reduction of N2 is thermodynamically ________ without ATP coupling

favorable

Breaking the triple bond in N2 requires a high amount of ________ energy, needing 16 ATP

activation

Nitrogenase is allosterically _______ by ______, so not active if energy charge is low

inhibited, ADP

A product of nitrogenase, _____, regulates _____ expression, more of the product inhibits

NH4+, gene

Nitrogen reductase is regulated by ______ modification, when the amino acid side chain is attached to a group, it becomes _____

covalent, inactive

Nitrate assimilation only occurs in _____ and _______, not animals

plants, prokaryotes

______ reductase transforms NO3 to NO2

Nitrate

______ reductase transforms NO2 to NH4+

Nitrite

Plants use nitrate or nitrite as _____ for their source of nitrogen

fertilizers

The cofactor involved in nitrate reductase is the _______ cofactor

molybdenum

The reduction of nitrite to ammonium requires ____ electrons than nitrate reductase, with _____ electrons compared to 2

more, 6

The cofactor involved in nitrate reductase is the _______ cofactor

seroheme

There are ____ reactions that ammonium attaches itself to
1. Carbamoyl-phosphate _________
2. Glutamate_____
3. Glutamine _______

synthetase, dehydrogenase, synthetase

Glutamate dehydrogenase utilizes ________ as a reactant to form glutamate

alpha-ketoglutarate

Glutamine synthetase is _____ dependent, there is no net ____

ATP, redox

Amino acids like Gly, Ala, Ser act as _____ regulators for glutamine synthetase

negative

The covalent modification of glutamine synthetase involves _______ which ______ GS

adenylylation, inactivates

In adenylylation, the ATP loses phosphates, and the remainding ____ attaches to OH group

AMP