drk1980
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Q. The Urea cycle requires how many ATP?
a)0
b)1
c)2
d)3
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| anjushree
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3
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| anjushree
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i.e ANS-----(d)
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| msyamp
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yup 3 two for carbamoyl phosphate and one at arginosuccintae synthase
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| drk1980
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great memory u both!
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| mjl1717
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And can someone comment on the 2 main genetic diseases directly associated with this cycle (although there are more then just 2). Also drk i like your epitaph.
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| drk1980
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Kaplan..
Genetic deficiency of 2 mitochondrial matrix enzymes of Urea Cycle:
CARBAMOYL PHOSPHATE SYNTHETASE I and ORNITIHINE TRANSCARBAMOYLASE.
both will hv similar manifestations:
>Hyperammonemia and Decreased BUN
>Inc glutamine blood levels---> since Urea cycle is suffering, the Minor pathway of ammonia metabolism takes over. The reaction is glutamate----(takes NH3)---->glutamine. Glutamine renally excretes NH3 as NH4+.
>Cerebral edema and symptoms of lethargy, convulsions...coma, death
Difference: Increased 'uracil & ORotic acid' blood and urine levels in ORnithine transcarbamoylase deficiency....since this enzyme catalyses conversion of carbamoyl phosphate into citrulline, in deficiency, excess build up of the substrate carbamoyl phosphate is shunted to its other function in denovo pyrimidine synthesis in making orotic acid, which is the main precursor of pyrimidines...after that is uracil monophosphate.
What intermediate produced in Urea cycle is also a part of Krebs cycle?
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| msyamp
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fumararat. i dot want to break the chain
which aminoacid supplies nitrogen to this urea cycle? directly and through nh4+
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| drk1980
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aspartate! wht is the other source of nitrogen to the urea cycle?
So is fumarate for TCA provided by Urea cycle? or...?
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| msyamp
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ya providded by urea cycle. other soure most commonly is alanine(via glutamate -- glutamate dehydrogenase) through remember?! glucose -alanine cycle.
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| drk1980
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Is this right?
Source of NH3 for the urea cycle- glutaminase and glutamate dehydrogenase
Entry of NH4+ into urea cycle thru- Aspartate and carbamoyl phosphate
Edited by drk1980 on 01/15/06 - 09:28 AM
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