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66 Cards in this Set
- Front
- Back
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nitrogen enters the biosphere via?
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nitrogen fixation
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What is the enzyme for nitrogen metabolism?
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nitrogenase
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what oxidizes NH4+ back to NO3-?
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nitrifying bacteria
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What enzyme catalyzes NH4+?
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carbamoyl phosphate synthase-1
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carbamoyl phosphate synthase is what kind of enzyme?
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mitochondrial
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what is the enzyme carbamoyl phosphate synthase activated by ?
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N-acetylglutamate
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what enzyme incorporates alpha keto glutarate into glutamate?
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glutamate dehydrogenase
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What enzyme changes glutamate to glutamine?
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glutamine synthase
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true or false, glutamine synthase has a lower affinity for NH4+ than glutamate dehydrogenase?
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false, it has a higher affinity
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The process by which fish release ammonia directly into the surroundings?
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ammoniotelic
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the process by which mammals release soluble products such as urea?
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ureotelic
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the process by which birds and reptiles release uric acid?
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uricotelic
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What is the condition when man produces uric acid from purine degradation
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gout
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what breaks down ammonia levels via some marine organisms and plants?
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urease
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What is the nitrogen balance?
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input=output
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What is the first thing removed in catabolism of amino acids?
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the amino group
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How are most amino acids changed into glutamate?
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via transamination with alpha KG
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amino acids-> glucose
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glucogonic
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amino acids-> acetyl CoA and Acetyl-CoA?
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ketogenic
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Transamination converts what to what ?
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a. acids to alpha keto acids
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What is the role in aminotransferases?
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catabolism and synthesis of amino acids
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Where are aminotransferases found?
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in cytosol and mitochondria
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What is the essential coenzyme of aminotransferases?
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pyridoxal phosphate
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What is the most common pair of aminotransferases?
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glutamate and alpha KG
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how are amino groups transported in muscles and other tissues?
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glutamine and alanine
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How are amino groups transfered to the liver and kidney?
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glutaminase
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where does the urea cycle occur in mammals?
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liver
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where does the first rxn of the uric acid cycle take place?
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mitochondrial matrix
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where do the other 3 rxn.s of the uric acid cycle take place?
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cytosol
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what is the enzyme that plays a central role in nitorgen metabolism?
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glutamate dehydrogenase
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What is the enzyme that converts glutamate to alpha KG?
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glutamate dehydrogenase
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rxn. 1 of the urea cycle produces what?
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ornithine transcarbamoylase
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rxn. 2 of the urea cycle produces what?
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synthethase: ATP-> AMP + PPi
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rxn. 3 the urea cycle produces what?
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lyase
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rxn. 4 of the urea cycle produces what?
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arginase
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What is the link btwn. the urea cycle and the TCA cycle?
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furmate from rxn. 3 of the urea cycle
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mitochondrial oxaloacetate can be transaminated into ?
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aspartate
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NH4+ is the regulator of the urea cycle, its presence says to do what?
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feed forward
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Induction of the cycle enzymes will do what?
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increase in protein metabolism
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how many ATP's are produced in the urea cycle?
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3/mole
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The urea cycle is highly exergonic and irreversible, true or false?
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true
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What enzyme catalyzes the following reaction:
carbamoyl-P + Ornithine -> citrilline |
ornithine transcarbamoylase
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What enzyme catalyzes the following reaction:
citrilline (gets transported out of the mitochondria)+ aspartate ->argininosuccinate |
synthetase, ATP -> AMP + PPi
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What enzyme catalyzes the following reaction:
arginosuccinate -> arginine + fumurate |
lyase
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What enzyme catalyzes the following reaction:
arginine -> ornithine + urea (ornitine is regenerated) |
arginase
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when arginase is hydrolyzed, what is formed?
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urea and ornithine
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What is the enzyme used for nitrogen fixation?
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nitrogenase
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Nitrogen assimilation converts what to what, ultimately?
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NO3 -> NO2- -> NH4+
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Nitrification converts what to what?
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NH4+ -> NO2- -> NO3
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Denitrification converts what to what?
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NO3 -> NO2- -> NO -> N2O -> N2
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Nitrogen Fixation converts what to what?
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N2 -> NH4+
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What is the name of this molecule:
NH4+ |
Ammonium. It is the ionized form of Ammonia. Breaks down plant protein. Occurs where water is acidic, not as harmful to fish as Ammonia.
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What is the name of this molecule:
NO2 |
Nitrogen Dioxide. An intermediate ionized form of nitrogen. Nitrifying bacteria can convert ammonia to nitrite, then to nitrate.
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What is the name of this molecule:
NO3 |
Nitrate. It is the last step in nitrification.
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What is the name of this molecule:
NO2- |
Nitrite
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What is the name of this molecule:
NO |
Nitric Oxide
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What is the name of this molecule:
N2O |
Nitrous Oxide
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What is the name of this molecule:
N2 |
molecular nitrogen
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What is the purpose of nitrification?
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Is the reduction of ammonia, which provides another way for organisms to obtain nitrogen.
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What is the purpose of denitrification?
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The nitrate ion (NO3-) and nitrite ion (NO2-) return nitrogen to the atmosphere.
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What is the purpose of nitrogen fixation?
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nitrogen fixation converts essentially unusable N2 to ammonia (which can be used in biosynthetic pathways) via the enzyme nitrogenase
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what is the purpose of nitrogen assimilation?
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it is used by plants that cannot independently undergo nitrogen fixation. It goes from nitrate, to nitrite, to ammonia.
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What is the name of the enzyme that catalyzes the hydrolysis of urea into carbon dioxide and water?
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urease
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what happens if you have excess protein?
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break down the protein into amino acids and excrete the nitrogen.
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hepatitis, hepatoxins, cirrosis are all caused by what?
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too much ammonia in the blood
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the gout is caused by?
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too much urea in the blood
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