Description : Lesch-Nyhan syndrome, the sex linked recessive disorder is due to the lack of the enzyme: (A) Hypoxanthine-guanine phosphoribosyl transferse (B) Xanthine oxidase (C) Adenine phosphoribosyl transferase (D) Adenosine deaminase
Last Answer : Answer : A
Description : The enzyme required for salvage of free purine bases is (A) Adenine phosphoribosyl transferase (B) Hypoxanthine guanine phosphoribosyl transferase (C) Both (A) and (B) (D) None of these
Last Answer : Answer : C
Description : Conversion of inosine monophosphate to xanthine monophosphate is catalysed by (A) IMP dehydrogenase (B) Formyl transferase (C) Xanthine-guanine phosphoribosyl transferase (D) Adenine phosphoribosyl transferase
Description : Increased urinary excretion of orotic acid can occur in deficiency of (A) Orotate phosphoribosyl transferase (B) OMP decarboxylase (C) Mitochondrial ornithine transcarbamoylase (D) Any of the above
Last Answer : Answer : D
Description : Orotic aciduria type II reflects the deficiency of the enzyme: (A) Orotate phosphoribosyl transferase (B) Orotidylate decarboxylase (C) Dihydroorotase (D) Dihydroorotate dehydrogenase
Last Answer : Answer : B
Description : Orotic aciduria type I reflects the deficiency of enzymes: (A) Orotate phosphoribosyl transferase and orotidylate decarboxylase (B) Dihydroorotate dehydrogenase (C) Dihydroorotase (D) Carbamoyl phosphate synthetase
Description : Methotrexate blocks the synthesis of thymidine monophosphate by inhibiting the activity of the enzyme: (A) Dihydrofolate reductase (B) Orotate phosphoribosyl transferase (C) Ribonucleotide reductase (D) Dihydroorotase
Description : All of the following statements about allopurinol are true except (A) It is a structural analogue of uric acid (B) It can prevent uric acid stones in the kidneys (C) It increases the urinary excretion of xanthine and hypoxanthine (D) It is a competitive inhibitor of xanthine oxidase
Description : In inherited deficiency of hypoxanthine guanine phosphoribosyl transferase (A) De novo synthesis of purine nucleotides is decreased (B) Salvage of purines is decreased (C) Salvage of purines is increased (D) Synthesis of uric acid is decreased
Description : All the following statements about primary gout are true except (A) Its inheritance is X-linked recessive (B) It can be due to increased activity of PRPP synthetase (C) It can be ... activity of hypoxanthine guanine phosphoribosyl transferase (D) De novo synthesis of purines is increased in it
Description : Salvage of purine bases is regulated by (A) Adenosine phosphoribosyl transferase (B) Hypoxanthine guanine phosphoribosyl transferase (C) Availability of PRPP (D) None of these
Description : A common substrate of HGPRTase, APRTase and PRPP glutamyl amidotransferase is (A) Ribose 5 phosphate (B) Phosphoribosyl pyrophosphate (C) Hypoxanthine (D) Adenosine
Description : Allopurinol lowers the plasma concentration of: A. Hypoxanthine B. Xanthine C. Uric acid D. All of the above
Last Answer : C. Uric acid
Description : Nitrosamine can deaminate (A) Cytosine to form uracil (B) Adenine to form xanthine (C) Guanine to form hypoxanthine (D) All of these
Description : The end product of purine catabolism in man is (A) Inosine (B) Hypoxanthine (C) Xanthine (D) Uric acid
Description : The nitrogenous base present in the RNA molecule is (A) Thymine (B) Uracil (C) Xanthine (D) Hypoxanthine
Description : A drug which prevents uric acid synthesis by inhibiting the enzyme xanthine oxidase is (A) Aspirin (B) Allopurinol (C) Colchicine (D) Probenecid
Last Answer : B
Description : The first reaction unique to purine nucleotide synthesis is catalysed by (A) PRPP synthetase (B) PRPP glutamyl amido transferase (C) Phosphoribosyl glycinamide synthetase (D) Formyl transferase
Description : Complete absence of hypoxanthine guanine phospharibosyl transferase causes (A) Primary gout (B) Immunodeficiency (C) Uric acid stones (D) Lesh-Nyhan syndrome
Description : Hybridoma cells are selected by culturing them in a medium containing (A) Adenine, guanine, cytosine and thymine (B) Adenine, guanine, cytosine and uracil (C) Hypoxanthine, aminopterin and thymine (D) Hypoxanthine, aminopterin and thymidine
Description : Free purine bases which can be salvaged are (A) Adenine and guanine (B) Adenine and hypoxanthine (C) Guanine and hypoxanthine (D) Adenine, guanine and hypoxanthine
Description : A substrate for enzymes of pyrimidine nucleotide biosynthesis is (A) Allopurinol (B) Tetracylin (C) Chloramphenicol (D) Puromycin
Description : Choose the correct statement about allopurinol: A. It is a purine antimetabolite with antineoplastic activity B. It is a competitive inhibitor of xanthine oxidase C. It is inactive itself ... D. Both allopurinol as well as its metabolite alloxanthine are noncompetitive inhibitors of xanthine oxidase
Last Answer : B. It is a competitive inhibitor of xanthine oxidase
Last Answer : (B) Allopurinol
Description : A copper containing oxidase is (A) Cytochrome oxidase (B) Flavin mononucleotide (C) Flavin adenine dinucleotide (D) Xanthine oxidase
Description : An enzyme which uses hydrogen acceptor as substrate is (A) Xanthine oxidase (B) Aldehyde oxidase (C) Catalase (D) Tryptophan oxygenase
Description : All the enzymes required for de novo synthesis of pyrimidine nucleotides are cytosolic except (A) Carbamoyl phosphate synthetase (B) Aspartate transcarbamoylase (C) Dihydro-orotase (D) Dihydro-orotate dehydrogenase
Description : Pyrimidine biosynthesis begins with the formation from glutamine, ATP and CO2, of (A) Carbamoyl aspartate (B) Orotate (C) Carbamoyl phosphate (D) Dihydroorotate
Description : 5-Phosphoribosyl-1-pyrophosphate is required for the synthesis of (A) Purine nucleotides (B) Pyrimidine nucleotides (C) Both (A) and (B) (D) None of these
Description : The major determinant of the overall rate of denovo purine nucleotide biosynthesis is the concentration of (A) 5-phosphoribosyl 1-pyrophosphate (B) 5-phospho β-D-ribosylamine (C) Glycinamide ribosyl-5-phosphate (D) Formylglycinamide ribosyl-5-phosphate
Description : The key substance in the synthesis of purine, phosphoribosyl pyrophosphate is formed by (A) α-D-ribose 5-phosphate (B) 5-phospho β-D-ribosylamine (C) D-ribose (D) Deoxyribose
Description : In humans, the principal metabolic product of pyrimidines is (A) Uric acid (B) Allantoin (C) Hypoxanthine (D) β-alanine
Description : Carbonic anhydrase is competitively inhibited by (A) Allopurinol (B) Acetazolamide (C) Aminopterin (D) Neostigmine
Description : Which of the following is a disease modifying antirheumatic drug whose active metabolite inhibits the enzyme dihydro-orotate dehydrogenase: A. Leflunomide B. Nimesulide C. Sulfasalazine D. Colchicine
Last Answer : A. Leflunomide
Description : A drug which prevents uric acid synthesis by inhibiting the enzyme Xanthine oxidase is (A) Aspirin (B) Allopurinal (C) Colchicine (D) Phenyl benzoate
Description : Hypouricaemia can occur in (A) Xanthine oxidase deficiency (B) Psoriasis (C) Leukaemia (D) None of these
Description : Mammals other than higher primates do not suffer from gout because they (A) Lack xanthine oxidase (B) Lack adenosine deaminase (C) Lack purine nucleoside phosphorylase (D) Possess uricase
Description : β -Aminoisobytyrate is formed from catabolism of (A) Cytosine (B) Uracil (C) Thymine (D) Xanthine
Description : Enzymic deficiency in β-aminoisobutyric aciduria is (A) Adenosine deaminase (B) Xanthine oxidase (C) Orotidylate decarboxylase (D) Transaminase
Description : An autosomal recessive disorder, xanthinuria is due to deficiency of the enzymes: (A) Adenosine deaminase (B) Xanthine oxidase (C) HGPRTase (D) Transaminase
Description : The correct sequence of the reactions of catabolism of adenosine to uric acid is (A) Adenosine→hypoxanthine→xanthine→uric acid (B) Adenosine→xanthine→inosine→uric acid (C) Adenosine→inosine→hypoxanthine→ xanthine uric acid (D) Adenosine→xanthine→inosine→hypoxanthine uric acid
Description : In humans purine are catabolised to uric acid due to lack of the enzyme: (A) Urease (B) Uricase (C) Xanthine oxidase (D) Guanase
Description : In humans end product of purine catabolism is (A) Uric acid (B) Urea (C) Allantoin (D) Xanthine
Description : Molybdenum is a cofactor for (A) Xanthine oxidase (B) Aldehyde oxidase (C) Sulphite oxidase (D) All of these
Description : Iron is present in all the following except (A) Peroxidase (B) Xanthine oxidase (C) Aconitase (D) Fumarase
Description : A molybdenum containing oxidase is (A) Cytochrome oxidase (B) Xanthine oxidase (C) Glucose oxidase (D) L-Amino acid oxidase
Description : Schardinger’s enzyme is (A) Lactate dehydrogenase (B) Xanthine dehydrogenase (C) Uric oxidase (D) L amino acid dehydrogenase
Description : Physostigmine is a competitive inhibitor of (A) Xanthine oxidase (B) Cholinesterase (C) Carbonic anhydrase (D) Monoamine oxidase
Description : Insulin degradation of disulfide bond formation is effected by (A) Pyruvate dehydrogenase (B) Xylitol reductase (C) Gutathione reductase (D) Xanthine oxidase
Description : Xanthuric acid is an abnormal metabolite of (A) Xanthine (B) Uric acid (C) Tyrosine (D) Tryptophan