module 12 Flashcards

1
Q

nitrogen fixation

A

carried out by cyanobacteria, converts N2 to ammonia

higher organisms get nitrogen in form of NH3, which is incorporated into several carbon skeletons

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2
Q

what can be formed from NH3

A

alpha keto glutarate. glutamate, aspartate, CO2, ATP

form glutamate, glutamine, and asparagine, reactions are reversible

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3
Q

protein turnover

A

allows for replacement of damaged proteins, rate of breakdown is important for controlling enzyme levels

important for nucleotides, non protein amino acids, and other nitrogen containing compounds

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4
Q

types of non protein amino acids

A

ornithine, citrulline, sarcosine

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5
Q

nitrogen excretion

A

most vertebrates excrete it as urea which is water soluble, uric acid and ammonia are also ways to excrete it

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6
Q

transamination -

A

transfer of amino group from one molecule to another, alpha keto acid generates an amino acid. They are pyridoxal phosphate and transaminase dependent.

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7
Q

oxidative deamination -

A

amine is removed from ammonia, catalyzed by glutamate dehydrogenase, NADH, NH4+ are generated

alpha ketoglutarate formed enters citric acid cycle, NADH goes into ETC or cellular respiration

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8
Q

where is glutamate dehydrogenase found

A

mitochondrial membrane

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9
Q

glutamine deamination -

A

one ammmonium freed by glutaminase to yield glutamate.

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10
Q

glutamine synthetase

A

found in liver, allows it to sequester ammonia as glutamine as urea biosynthesis becomes overwhelmed, allows liver to detoxify amines

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11
Q

glutamate dehydrogrenase -

A

passes extra nitrogen to urea cycle in liver.

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12
Q

glucose alanine shuttle -

A

transfers ammonia to liver for conversion to urea.

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13
Q

how do most tissues use glutamate

A

most tissues convert glutamate to glutamine using ammonia and atp. This glutamine is then moved into the liver

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14
Q

what happens to glutamine in the liver

A

glutaminase releases nitrogen from glutamine, regenerating glutamate and moving NH4 to urea cycle

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15
Q

glucose alanine shuttle muscle step 1

A

ammonium passed to alpha ketoglutarate, converting it to glutamate, which transaminates pyruvate to form alanine that moves into the liver.

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16
Q

glucose alanine muscle shuttle step 2

A

Alanine is then converted to pyruvate, reforming glutamate. Pyruvate produces glucose through gluconeogeneis. This glucose goes through glycolysis in the muscle to produce pyruvate.

17
Q

advantage of uric acid

A

It is not water soluble, allowing it to be excreted by uricotelic organisms

18
Q

what does oxidative deamination need in order to take place

A

pyridoxal phosphate

19
Q

importance of urea

A

it helps maintain pH balance in mammals

20
Q

carbamoyl phosphate

A

created by reaction of NH4 and HCO3, requires 2 ATP. N-acetylglutamate is also required

21
Q

formation of N-acetylglutamate

A

produced in the presence of extra acetyl CoA and glutamic acid, signaling molecule for carbamoyl phosphate synthetase

22
Q

Urea Cycle reactants and products

A

requires 3 ATP (energy expensive), produces urea and fumarate, requires 5 enzymes