Multiple Choice Question on Metabolism and Disposal of Urea, Creatinine,
and Uric Acid
1) The urea molecule consists of two nitrogens and one carbon atom. The first nitrogen atom is derived from the free ammonium ion and the second is from an amino acid.
The amino acid that donates the second amino group for the formation of urea is................................
a) Arginineb) Aspartate
c) Glutamate
d) Ornithine
b) Deamidation of histidine catalyzed by the enzyme histidase
c) Deamidation of serine and threonine by a PLP requiring enzyme serine dehydratase
d) All of the above
b) The presence of N-acetyl glutamate inhibits the activity of the CPS I enzyme
c) Two molecules of ATP are required for this reaction
d) The reaction occurs in mitochondria
b) Aspartate: Oxaloacetate
c) Alanine: Pyruvate
d) None of the above
2) The free ammonium group (NH4+) is derived from the following processes:
a) Oxidative deamination of Glutamine catalyzed by enzyme glutamate dehydrogenaseb) Deamidation of histidine catalyzed by the enzyme histidase
c) Deamidation of serine and threonine by a PLP requiring enzyme serine dehydratase
d) All of the above
3) The first step in the urea cycle is a condensation of CO2, ammonia, and ATP to form carbamoyl phosphate.
The following are true regarding the formation of carbamoyl phosphate, Except:
a) The reaction is catalyzed by a rate-limiting enzyme carbamoyl phosphate synthase-Ib) The presence of N-acetyl glutamate inhibits the activity of the CPS I enzyme
c) Two molecules of ATP are required for this reaction
d) The reaction occurs in mitochondria
4) Which of the following amino acid: keto acid pair bridges the urea cycle with the tricarboxylic acid cycle for the maintenance of the nitrogen and amino acid pool?
a) Glutamate: Alpha-ketoglutarateb) Aspartate: Oxaloacetate
c) Alanine: Pyruvate
d) None of the above
5) Four Adenosine triphosphate equivalents are required for the formation of urea in the urea cycle.
Which of the following enzymes utilize the ATPs?
a) Carbamoyl Phosphate synthase I
b) Ornithine Transcarbamoylase
c) Argininosuccinate synthase
d) Ariginosuccinase
b) antiport that exchanges arginine with ornithine
c) symport that co-transport citrulline with ornithine
d) antiport that exchanges citrulline with ornithine
a) Carbamoyl Phosphate synthase I
b) Ornithine Transcarbamoylase
c) Argininosuccinate synthase
d) Ariginosuccinase
b) Ornithine Transcarbamoylase
c) Argininosuccinate synthase
d) Ariginosuccinase
b) Phenylbutyrate
c) Arginine
d) Ornithine
10) The following conditions lead to the hyperammonemia
a) Chronic Liver Cirrhosis
b) GI bleeding
c) Deficiency of CPS I
d) All of the above
b) Arginine
c) Glycine
d) Methionine
b) CK-MB
c) CK-BB
d) None of the above
b) CK-MB
c) CK-BB
d) None of the above
b) The concentration of creatinine is fairly constant and relative to body muscle mass
c) Creatinine is freely filtered through the glomerular membrane
d) Creatinine is not secreted by kidney tubules
b) estimation of glomerular filtration rate
b) Ornithine Transcarbamoylase
c) Argininosuccinate synthase
d) Ariginosuccinase
6) The carbamoyl-phosphate is synthesized in the mitochondria and subsequently converted into citrulline. The remainder of the steps occurs in the cytosol requiring the transport of citrulline into the cytosol. The mitochondrial transporter is a.............................................
a) symport that co-transport arginine with ornithineb) antiport that exchanges arginine with ornithine
c) symport that co-transport citrulline with ornithine
d) antiport that exchanges citrulline with ornithine
7) The deficiency of which of the following enzymes urea cycle results in impaired synthesis of urea, accumulation of ammonia (hyperammonemia), and orotic aciduria?
b) Ornithine Transcarbamoylase
c) Argininosuccinate synthase
d) Ariginosuccinase
8) The deficiency of which of the following enzyme causes Citrullinemia- a condition with an accumulation of citrulline in the blood?
a) Carbamoyl Phosphate Ib) Ornithine Transcarbamoylase
c) Argininosuccinate synthase
d) Ariginosuccinase
9) Which of the following compound is administered to patients with urea cycle defects to remove ammonia?
a) Inulinb) Phenylbutyrate
c) Arginine
d) Ornithine
10) The following conditions lead to the hyperammonemia
a) Chronic Liver Cirrhosis
b) GI bleeding
c) Deficiency of CPS I
d) All of the above
11) The creatine synthesis begins in the kidney and is completed liver and requires three different amino acids for its formation. The creatine undergoes phosphorylation to form creatine phosphate in various tissue.
The following amino acids are required for its synthesis EXCEPT:
a) Alanineb) Arginine
c) Glycine
d) Methionine
12) The interconversion of creatine and creatine phosphate is catalyzed by an enzyme creatine kinase. Creatine kinase has three different isoenzymes.
Which of the following isoenzyme is present in heart tissue that is elevated in myocardial infarction?
a) CK-MMb) CK-MB
c) CK-BB
d) None of the above
13) The interconversion of creatine and creatine phosphate is catalyzed by an enzyme creatine kinase. Creatine kinase has three different isoenzymes.
Which of the following isoenzyme is present in heart tissue that is elevated in skeletal muscle atrophy?
a) CK-MMb) CK-MB
c) CK-BB
d) None of the above
14) Creatinine is a compound formed by a spontaneous cyclization of creatine phosphate in the brain and muscles.
The following statement is true for creatinine, Except:
a) One to two percent of Creatine phosphate is irreversibly converted to creatinineb) The concentration of creatinine is fairly constant and relative to body muscle mass
c) Creatinine is freely filtered through the glomerular membrane
d) Creatinine is not secreted by kidney tubules
15) Creatinine clearance is used for............................................
a) estimation of renal blood flowb) estimation of glomerular filtration rate
c) evaluation of nephrolithiasis
d) None of the above
b) Increased lactate levels and chronic alcoholism
c) Acute and Chronic Renal Disease
d) All of the above
17) Which of the following amino
acids have an important role in the transport of amino groups from peripheral
tissues to the liver?
Multiple Choice Answers:-
1-b) Aspartate
2-d) All of the above
3- b) The presence of N-acetyl glutamate inhibits the activity of the CPS I enzyme
4- b) Aspartate: Oxaloacetate
5-a) Carbamoyl Phosphate synthase I &c) Argininosuccinate synthase
6- d) antiport that exchanges citrulline with ornithine
7- b) Ornithine Transcarbamoylase
8- c) Argininosuccinate synthase
9- b) Phenylbutyrate
10- d) All of the above
11- a) Alanine
12- b) CK-MB
13- a) CK-MM
14- d) Creatinine is not secreted by kidney tubules
17-c) Glutamine
18-a) Amino acids
19-d) Gluconeogenesis
d) None of the above
16) Uric acid is the excretory end product of purine metabolism.
Which of the following condition lead to the increased production of uric acid?
a) Hypoxanthine- Guanosine phosphoribosyltransferaseb) Increased lactate levels and chronic alcoholism
c) Acute and Chronic Renal Disease
d) All of the above
17) Which of the following amino
acids have an important role in the transport of amino groups from peripheral
tissues to the liver?
a) Serine
b) Methionine
c) Glutamine
d) Arginine
18) The following metabolite is
excreted via urine to maintain the nitrogen balance, Except:
a) Amino acids
b) Creatinine
c) Urea
d) Ammonia
19) In citrullinemia- a problem in
the urea cycle, which of the following pathway is suppressed?
a) Glycolysis
b) Glycogenesis
c) Glycogenolysis
d) Gluconeogenesis
20) The Urea cycle is the most
energy-efficient cycle. It requires ATP for the continuation of the cycle.
Identify an intermediate that utilizes ATP for the formation:
a) Arginine
b) Ornithine
c) Citrulline
d) Arginine succinate
21) Which of the following is the end product of purine metabolism in humans?
a) Xanthine
b) Uric acid
c) Urea
d) Allantoin1-b) Aspartate
2-d) All of the above
3- b) The presence of N-acetyl glutamate inhibits the activity of the CPS I enzyme
4- b) Aspartate: Oxaloacetate
5-a) Carbamoyl Phosphate synthase I &c) Argininosuccinate synthase
6- d) antiport that exchanges citrulline with ornithine
7- b) Ornithine Transcarbamoylase
8- c) Argininosuccinate synthase
9- b) Phenylbutyrate
10- d) All of the above
11- a) Alanine
12- b) CK-MB
13- a) CK-MM
14- d) Creatinine is not secreted by kidney tubules
15- b) estimation of glomerular filtration rate
16- d) All of the above17-c) Glutamine
18-a) Amino acids
19-d) Gluconeogenesis
Answer
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