TOTW #24 - Biochemistry Start QuizPage 1 of 23 Which of the following is a start codon in the process of translation? UAA UAG UGA AUG Page 2 of 23 Which of the following glucose transporters is insulin-dependent? GLUT-1 GLUT-2 GLUT-3 GLUT-4 Page 3 of 23 Which of the following is false regarding gluconeogenesis? Stimulated by glucagon Rate limiting enzyme is Fructose 1,6-bisphosphatase Inhibited by insulin Occurs in a postprandial state Page 4 of 23 Inborn deficiency of glucose-6-phosphatase results in: Von Gierke disease Pompe disease Cori disease Andersen disease Page 5 of 23 Which of the following anti-TB drugs causes vitamin B6 deficiency and has to be co-administered with pyridoxine? Rifampicin Ethambutol Isoniazid Pyrazinamide Page 6 of 23 A 53 year old man presented to the clinic with diarrhoea, dementia and a dermatitis especially on sun-exposed areas of his skin. What is your diagnosis? What vitamin deficiency causes this condition? Scurvy, vitamin C deficiency Pellagra, vitamin B3 (niacin) deficiency Beriberi, vitamin B1(thiamine) deficiency Xerophthalmia, vitamin A deficiency Page 7 of 23 Which enzyme is directly inhibited by the cholesterol-lowering drugs known as statins? HMG-CoA reductase HMG-CoA synthase Mevalonate kinase Squalene synthase Page 8 of 23 Which metabolic product is elevated in individuals with maple syrup urine disease due to a deficiency in the branched-chain alpha-keto acid dehydrogenase complex? Homocysteine Branched-chain amino acids Phenylalanine Tyrosine Page 9 of 23 Which coenzyme is derived from vitamin B3 and is crucial in redox reactions? FAD NAD+ Coenzyme A Tetrahydrofolate Page 10 of 23 Which process is the primary function of the enzyme ribonucleotide reductase? Synthesis of ribose-5-phosphate Conversion of ribonucleotides to deoxyribonucleotides Degradation of purines Synthesis of ATP Page 11 of 23 Which enzyme is deficient in patients with Lesch-Nyhan syndrome, leading to excessive production of uric acid? Adenosine deaminase Xanthine oxidase Hypoxanthine-guanine phosphoribosyltransferase (HGPRT) Purine nucleoside phosphorylase Page 12 of 23 A 5-year-old girl presents with intellectual disability and self-mutilating behaviours. She has a history of gout and uric acid kidney stones. Laboratory results show hyperuricemia. What is the most likely diagnosis? Gaucher disease Maple syrup urine disease Phenylketonuria Lesch-Nyhan syndrome (HGPRT deficiency) Page 13 of 23 Which of the following drugs prevents uric acid synthesis by inhibiting the enzyme xanthine oxidase? Aspirin Allopurinol Colchicine Probenecid Page 14 of 23 Oxidation of which of the following substances in the body yields the most calories? Glucose Glycogen Protein Lipids Page 15 of 23 The α-D-glucose and β-D-glucose are: Stereoisomers Epimers Anomers Keto-aldo pairs Page 16 of 23 Which of the following is an aromatic amino acid? Lysine Tyrosine Taurine Arginine Page 17 of 23 A 10-day-old male infant presents with cyanotic episodes and recurrent generalized convulsions; the odor of burned sugar from the body and urine is also noted. Plasma and urine amino acid analysis disclosed a marked increase in the concentration of branched chain amino acids (BCAA). What is the diagnosis? Pompe disease Danon disease Maple syrup urine disease. Tay-sachs disease Page 18 of 23 Which of the following is a 39-residue hormone of the anterior pituitary gland? Glucagon Bradykinin Corticotropin Insulin Page 19 of 23 In which of the following are glucose residues linked by β1 and 4 glycosidic bonds? Starch Cellulose Glycogen Amylose Page 20 of 23 Which of the following is involved in carrying genetic information from DNA for protein synthesis? sn-RNA r-RNA m-RNA t-RNA Page 21 of 23 Which of the following is an intracellular second messenger? Glycine Glutamate Acetylcholine IP3 Page 22 of 23 Which of the following is the first process involving absorption of physical energy by retinal receptors after being exposed to visual stimulus? Coding Adaptation Transduction Reception Page 23 of 23 A 21 year old presents at the outpatient department with complaints of general body weakness, joint swelling and pain, recurrent URTIs, bleeding while brushing her teeth and feeling looseness in her teeth. This follows a dietary change after she moved out of her parents’ house. On examination, her gums appeared as below. What is the patient likely suffering from? Niacin deficiency Gingivitis Vitamin C deficiency Pellagra Multiple Authors | WebsiteTOTW #26 - MicrobiologyTOTW #25 - PsychiatryTOTW #23 - HaematologyTOTW #22 - Embryology Previous Post TOTW #23 - Haematology Next Post TOTW #25 - Psychiatry
