Sunday, October 28, 2012

Multiple Choice Questions- Amino acid metabolism

Q.1- Which of the following is a common compound shared by the TCA cycle and the Urea cycle?
a) α- Keto glutarate
b) Succinyl co A
c) Oxalo acetate
d) Fumarate
Q.2-Which of the followings is a common nitrogen acceptor for all reactions involving transaminases?
a) α- Keto glutarate
b) Pyruvate
c) Oxaloacetate
d) Acetoacetate
Q.3- In a 55- year-old man, who has been diagnosed with cirrhosis of liver, Ammonia is not getting detoxified and can damage brain. Which of the following amino acids can covalently bind ammonia, transport and store in a non toxic form?
a) Aspartate
b) Glutamate
c) Serine
d) Cysteine
Q.4- In a new born presenting with refusal to feeds and irritability, a deficiency of Cystathionine –β- synthase has been diagnosed, which of the following compounds is expected to be elevated in blood?
a) Serine
b) Glutamate
c) Homocysteine
d) Valine
Q.5 -A 3- month-old child is being evaluated for vomiting and an episode of convulsions, Laboratory results show hyperammonemia and Orotic aciduria. Which of the following enzyme defect is likely to be there?
a) Glutaminase
b) Arginase
c) Argino succinic acid synthase
d) Ornithine Transcarbamoylase
Q.6- Which out of the following amino acids is not converted to Succinyl co A?
a) Methionine
b) Valine
c) Isoleucine
d) Histidine
Q.7-All of the following compounds are synthesized by transmethylation reactions, except-
a) Choline
b) Epinephrine
c) Creatine
d) Ethanolamine
Q.8- A patient diagnosed with Hart Nup disease, (due to deficiency of transporter required for the absorption of amino acid tryptophan), has been brought with skin rashes and suicidal tendencies. Tryptophan is a precursor for many compounds, the deficiencies of which can cause the said symptoms. Which out of the following compounds is not synthesized by tryptophan?
a) Serotonin
b) Epinephrine
c) Melatonin
d) Niacin
Q.9- Histamine, a chemical mediator of allergies and anaphylaxis, is synthesized from amino acid Histidine by which of the following processes?
a) Deamination
b) Decarboxylation
c) Transamination
d) Dehydrogenation
Q.10- The synthesis of all of the following compounds except one is deficient in a patient suffering from Phenylketonuria-
a) Melanin
b) Melatonin
c) Catecholamines
d) Thyroid hormone
Q.11- The diet of a child suffering from Maple syrup urine disease (an amino acid disorder), should be low, in which out of the following amino acids content?
a) Branched chain amino acids
b) Phenylalanine Alanine
c) Methionine
d) Tryptophan
Q.12- Which out of the following amino acids in not required for creatine synthesis?
a) Methionine
b) Serine
c) Glycine
d) Arginine
Q.13- All of the following substances are synthesized from Cysteine, except-
a) Taurine
b) Mercaptoethanolamine
c) Melanin
d) Pyruvate
Q.14- Urea is synthesized in -
a) Cytoplasm
b) Mitochondria
c) Both cytoplasm and mitochondria
d) In lysosomes
Q.15-Blood urea decreases in all of the following conditions, except-
a) Liver cirrhosis
b) Pregnancy
c) Renal failure
d) Urea cycle disorders
Q.16- All of the following amino acids are donors of one carbon compounds except-
a) Histidine
b) Tyrosine
c) Tryptophan
d) Serine
Q.17- The two nitrogen of urea are derived from-
a) Aspartate and Ammonia
b) Glutamate and ammonia
c) Argino succinate and ammonia
d) Alanine and ammonia
Q.18- Which out of the following amino acids is not required for the synthesis of Glutathione?
a) Serine
b) Cysteine
c) Glutamic acid
d) Glycine
Q.19- The first line of defence in brain in conditions of hyperammonemia is-
a) Urea formation
b) Glutamine synthesis
c) Glutamate synthesis
d) Asparagine formation
Q.20- Which coenzyme out of the followings is required for the oxidative deamination of most of amino acids?
a) Folic acid
b) Pyridoxal- P
c) FMN
d) FAD
Q.21-Chose the incorrect statement about amino acid Glycine-
a) One carbon donor
b) Required for the synthesis of haem
c) Forms oxalates upon catabolism
d) Both glucogenic as well as ketogenic
Q.22- Which out of the followings is required as a coenzyme for the transamination reactions?
a) Coenzyme A
b) Pyridoxal-P
c) Folic acid
d) Cobalamine
Q.23- A patient diagnosed with Homocystinuria should be supplemented with all of the following vitamins except-
a) Vitamin C
b) Folic acid
c) Vitamin B12
d) Pyridoxal- P
Q.24- In a patient suffering from Cystinuria, which out of the following amino acids is not seen in urine of affected patients?
a) Arginine
b) Methionine
c) Lysine
d) Ornithine
Q.25- Positive nitrogen balance is seen in all of the following conditions except-
a) Pregnancy
b) Growth
c) Fever
d) Convalescence
Q.26- The L-amino acids are absorbed from intestine by-
a) Active transport
b) Passive diffusion
c) Pinocytosis
d) Facilitated diffusion
Q.27- A child presented with increased frequency of urination, photophobia and impairment of vision. Which out of the following defects could be responsible for the said symptoms?
a) Tyrosinosis
b) Cystinosis
c) Alkaptonuria
d) Albinism
Q.28- Which out of the following statements about Glutamate dehydrogenase is correct?
a) Required for transamination reactions
b) Universally present in all the cells of the body
c) Can utilize either of NAD+ /NADP+
d) Catalyzes conversion of glutamate to glutamine
Q.-29-A child was brought to paediatric OPD with complaint of passage of black colored urine. A disorder of Phenylalanine metabolism was diagnosed. A low phenylalanine diet and a supplementation of vitamin C were recommended. Which enzyme defect is expected in this child?
a) Phenyl alanine hydroxylase
b) Tyrosine transaminase
c) Homogentisic acid oxidase
d) Hydrolase
Q.30- Dopamine is synthesized from which of the following amino acids?
a) Tyrosine
b) Tryptophan
c) Histidine
d) Methionine
Q.31- In mammalian tissue serine can be a biosynthetic precursor for which amino acid?
a) Methionine
b) Glycine
c) Arginine
d) Lysine
Q.32- Hydroxylation of Phenyl Alanine to Tyrosine requires all except-
a) Glutathione
b) Tetra hydrobiopterin
c) Molecular oxygen
Q.33- The amino acid that undergoes oxidative deamination at a highest rate is-
a) Glutamine
b) Glutamate
c) Aspartate
d) Alanine
Q.34- All of the following statements regarding serotonin are true except-
a) Causes vasodilatation
b) Causes broncho constriction
c) Metabolized to 5-hydroxy Indole acetic acid
d) Causes diarrhoea
Q.35- Choose the incorrect statement about cysteine-
a) Carbon skeleton is provided by serine
b) Sulfur group is provided by Methionine
c) Forms Hippuric acid for detoxification of xenobiotics
d) Required for Bile salt formation


1)-d, 2)-a, 3)- b, 4) -c, 5)-d, 6) -d, 7)-d, 8)-b, 9) -b, 10)-b, 

11)-a), 12)-b, 13)-c, 14)-c, 15)-c,16)-b, 17)-a, 18)-a, 19)-b, 20)-c

21)-d, 22)-b,23)-a,24)-b, 25)-c, 26)-a, 27)-b,28)-c, 29)-c, 30)-a

31)-b,32)-a,33)-b, 34)-a,35)-c

------------------------------------------ Best Wishes: Dr.Ehab Aboueladab, Tel:01007834123, ------------------------------------------
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