MCQS ON PROTEIN METABOLISM II 1 The coenzyme

MCQS ON PROTEIN METABOLISM II

1. The coenzyme essential for transamination reaction is a. THF b. PLP c. TPP d. NAD + 2. Glycine in combination with which of the following amino acids forms glutathione a. glutamate and cysteine b. glutamine and cysteine c. aspartate and methionine d. aspargine andv tyrosine 3. The high energy compound creatine phosphate is synthesised from the following amino acids a. glycine, lysine and histidine b. glycine, tyrosine and proline c. glycine, arginine and methionine d. glycine, serine and histidine

4. Maple syrup urine disease occurs due to the enzyme defect in the metabolism of following amino acids a. Sulphur amino acids b. Hydroxy amino acids c. Acidic amino acids d. Branched amino acids 5. The branched chain amino acid that is exclusively ketogenic is a. Leucine b. valine c. isoleucine d. valine and isoleucine 6. Which of the following molecules serves as the methyl group donor in transmethylation reactions a. Methionine b SAM c. SAH d. ethanolamine

7. The number of high energy phosphates consumed in the synthesis of SAM is a. 1 b. 2 c. 3 d. 4 8. All of the following products are formed through transmethylation reactions , except a. Creatine b. melatonin c. anserine d. norepinephrine 9. Elevated homocysteine levels are associated with a risk of a. Bronchiectasis b. nephrotic syndrome c. coronary artery disease d. diabetes mellitus 10. All the following compounds are produced from cysteine metabolism , except a. Glutathione b. creatine c. taurine d. PAPS

11. One of the following substances serve as the source of sulfate groups a. PAPS b. SAM c. glutathione d. creatine 12. The inborn error of sulphur containing amino acid metabolism that causes the formation of kidney stones is a. Cystinosis b. homocystinuria type I c. Cystinuria d. all of the above 13. In cystinuria the following amino acids are excreted a. taurine and glycine b. glycine, alanine and cysteine c. ornithine, arginine, lysine and cysteine d. phenylalanine, tyrosine, tryptophan and cysteine

14. The enzyme defect in homocystinuria type I is a. Cystathioninase b. cystathionine synthase c. α keto acid dehydrogenase d. desulphinase 15. FIGLU excretion test is done to identifty the deficiency of the vitamin a. B 12 B. thiamine c. Folate d. pyridoxine 16. Formiminoglutamate ( FIGLU) is formed in the metabolism of a. aspartate b. glutamate c. arginine d. histidine 17. All the following statements about histamine, a derivative of histidine are true, except a. It acts as vasodilator and hence lowers the blood pressure b. It stimulates gastric HCl secretion c. In high concentration it cause allergic reactions d. It cause platelet aggregation

18. Histidine, arginine and proline during the course of their metabolism produce the following amino acid a. Glutamate b. aspartate c. lysine d. serine 19. The following amino acid directly takes part in the synthesis of urea a. Histidine b. lysine c. arginine d. methionine 20. The ‘ wonder molecule’ nitric oxide is synthesised from a. Arginine b. histidine c. lysine d. cysteine 21. The conversion of phenylalanine to tyrosine requires the cofactor a. thioredoxin b. biopterin c. pteridin d. all the above

22. The end products of phenylalanine and tyrosine degradation are a. Fumarate and acetoacetate b. Malate and α ketoglutarate c. Succinate and oxaloacetate d. Acetyl Co. A propionyl Co. A 23. All the following substances are synthesised from phenyalanine and tyrosine, except a. thyroid hormones b. catecholamines c. melanin d. glucocorticoids 24. The following substance is not a catecholamine a. Ethanolamine b. dopamine c. epinephrine d. norepinephrine 25. Norepinephrine is converted to epinephrine by a. Phosphorylation b. hydroxylation c. carboxylation d. methylation

26. Parkinsonism is associated with an impairment in synthesis of a. Epinephrine b. dopamine c. etanolamine d. serotonin 27. Thyroid hormones ( T 3 and T 4) are synthesised from tyrosine residues of the following protein a. Thyroglobulin b. haptoglobin c. albumin d. all of the above 28. The enzyme that synthesises the pigment , melanin from tyrosine is a. Tyrosinase b. tyrosine transaminase c. homogentisate oxidase d. all the above 29. Phenylketonuria occurs due to the defect of the following enzym a. Phenylalanine hydroxylase b. tyrosine hydroxylase c. . Tyrosinase d. homogentisate oxidase

30. Mental retardation is common in following disease a. Alkaptonuria b. albinism c. phenylketonuria d. all the above 31. The following investigations are a diagnostic test to identify phenylketonuria a. Phenylalanine levels in blood b. Ferric chloride test c. Guthrie test d. All the above 32. If detected early, mental retardation can be avoided in patients of PKU by providing the following dietary regimen, a diet that is a. rich in phenylalanine and tyrosine b. low in phenylalanine and high in tyrosine c. low in phenylalanine and tyrosine d. high in phenylalanine and low in tyrosine

33. The following disease is popularly known as ‘black urine disease’ a. Phenylketonuria b. alkaptonuria c. albinism d. tyrosinemia type I 34. The enzyme defect in alkaptonuria a. Homogentisate oxidase b. tyrosinase c. tyrosine aminotransferase d. maleylacetoacetate isomerase 35. Ochronosis is associated with the following disease a. Alkaptonuria b. phenylketonuria c. albinism d. tyrosinemia type II 36. In albinism the following substance is either absent or defective a. Noradrenaline b. biopterin c. melanin d. dopamine

37. Albinism is characterised by all the following , except a. Albinos are more prone to skin cancers b. photophobia c. their eyesight is normal d. enzyme tyrosine hydroxylase is absent 38. The enzyme that cleaves the indole nucleus during tryptophan catabolism is a. Tryptophan pyrrolase b. kynurenine formamidase c. hydroxyanthranalite oxidase d. kynureninase 39. NAD+ and NADP+ are derived from the amino acid a. Tyrosine b. tryptophan c. histidine d. arginine

39. Which of the following enzymes of tryptophan metabolism is dependant on pyridoxal phosphate(PLP) a. Tryptophan pyrrolase c. hydroxyanthranalite oxidase b. kynurenine formamidase d. kynureninase 40. The product of tryptophan metabolism which is known to induce sleep is a. Serotonin b. melatonin c. NAD+ d. NADP+ 41. The enzyme that degrades serotonin to hydroxyindoleacetate is a. Monoamino oxidase b. kynureninase c. Tryptophan pyrrolase d. tryptophan hydroxylase

42. All the following actions are performed by serotonin, except a. it acts as excitatory neurotransmitter in brain b. it is a potent vasoconstrictor and causes smooth muscle contraction of arterioles and bronchioles c. It causes insomnia d. Induces paralysis and causes the release of peptide hormones from GIT 43. The following tissue produces high amounts of serotonin a. brain b. liver c. heart d. intestine 44. Carcinoid tumours (argentaffinomas) are usually seen in a. GI tract b. heart c. Brain d. lungs

45. The substance responsible for diurnal variations is a. serotonin b. melatonin c. epinephrine d. dopamine 46. Hartnup’s disease is associated with defective absorption of the following amino acid a. Tryptophan b. proline c. arginine d. lysine