Description : Erythromycin binds to 50 S ribosomal sub unit and (A) Inhibits binding of amino acyl tRNA (B) Inhibits Peptidyl transferase activity (C) Inhibits translocation (D) Causes premature chain termination
Last Answer : Answer : C
Description : In prokaryotes, chloramphenicol (A) Causes premature release of the polypeptide chain (B) Causes misreading of the mRNA (C) Depolymerises DNA (D) Inhibits peptidyl transferase activity
Last Answer : Answer : A
Description : Erythromycin acts on ribosomes and inhibit (A) Formation of initiation complex (B) Binding of aminoacyl tRNA (C) Peptidyl transferase activity (D) Translocation
Last Answer : Answer : D
Description : Select the antibiotic which inhibits bacterial protein synthesis by interfering with translocation of elongating peptide chain from acceptor site back to the peptidyl site of the ribosome so that ... chain is prematurely terminated: A. Chloramphenicol B. Erythromycin C. Tetracycline D. Streptomycin
Last Answer : B. Erythromycin
Description : Tetracylin prevents synthesis of polypeptide by (A) Blocking mRNA formation from DNA (B) Releasing peptides from mRNA-tRNA complex (C) Competing with mRNA for ribosomal binding sites (D) Preventing binding of aminoacyl tRNA
Description : Translocation of the newly formed peptidyl tRNA at the A site into the empty P site involves (A) EF-II, GTP (B) EF-I, GTP (C) EF-I, GDP (D) Peptidyl transferase, GTP
Description : Which of the following step of translation does not consume a high energy phosphate bond? (a) Peptidyl transferase reaction (b) Aminoacyl tRNA binding to A-site (c) Translocation (d) Amino acid activation
Last Answer : (b) Aminoacyl tRNA binding to A-site
Last Answer : (a) Peptidyl transferase reaction
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 : Insulin regulates fatty acid synthesis by (A) Dephosphorylating of acetyl CoA carboxylase (B) Activating phosphorylase (C) Inhibiting malonyl CoA formation (D) Controlling carnitine-Acyl CoA transferase activity
Description : Peptidyl transferase activity of 50 S ribosomal subunits is inhibited by (A) Rifampicin (B) Cycloheximide (C) Chloramphenicol (D) Erythromycin
Description : Peptidyl transferase activity is present in (A) 40 S ribosomal subunit (B) 60 S ribosomal subunit (C) eEF-2 (D) Amino acyl tRNA
Last Answer : Answer : B
Description : Peptidyl transferase activity is located in (A) Elongation factor (B) A charged tRNA molecule (C) Ribosomal protein (D) A soluble cytosolic protein
Description : Nonsense codons bring about (A) Amino acid activation (B) Initiation of protein synthesis (C) Termination of protein synthesis (D) Elongation of polypeptide chains
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 : 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 : After formation of a peptide bond, mRNA is translocated along the ribosome by (A) eEF-1 and GTP (B) eEF-2 and GTP (C) Peptidyl transferase and GTP (D) Peptidyl transferase and ATP
Description : The α-amino group of the new amino acyl tRNA in the A site carries out a nucleophilic attack on the esterified carboxyl group of the peptidyl tRNA occupying the P site. This reaction is catalysed by (A) DNA polymerase (B) RNA polymerase (C) Peptidyl transferase (D) DNA ligase
Last Answer : (B) Allopurinol
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 : Which of the following molecule catalyzes the transpeptidation reaction? A.RNA polymerase B.Peptidyl transferase C.DNA ligase D.DNA polymerase
Last Answer : B.Peptidyl transferase
Description : Peptidyl transferase a) Is a 23s rRNA b) forms peptide bonds c) component of ribosome d) all the three
Last Answer : d) all the three
Description : Regulation of ACTH secretion occurs through (A) Corticotropin releasing hormone (CRH) and corticotropin release inhibiting hormone (CRIH) of hypothalamus (B) Feedback inhibition by cortisol (C) CRH and feedback inhibition by cortisol (D) CRIH and feedback inhibition by cortisol
Description : Secretion of prolactin is regulated by (A) Feedback inhibition (B) Prolactin releasing hormone (C) Prolactin release inhibiting hormone (D) All of these
Description : Growth hormone is released by (A) Somatostatin (B) Growth hormone releasing hormone (C) Prolactin release inhibiting hormone (D) Luteinizing releasing hormone
Description : Which binding is inhibited by pactamycin? A- Aminoacyl-tRNA to the A-site of 30S subunit B- Initiator-tRNA to 30S/40S initiation complexes C- Peptidyl t-RNA to the 50S subunit D- Formation of peptide bond in P site
Last Answer : Initiator-tRNA to 30S/40S initiation complexes
Description : The enzyme amino acyl tRNA synthetase is involved in (A) Dissociation of discharged tRNA from 80S ribosome (B) Charging of tRNA with specific amino acids (C) Termination of protein synthesis (D) Nucleophilic attack on esterified carboxyl group of peptidyl tRNA
Description : Two cyclic polypeptide antibiotics are a. Vancomycin and streptomycin. b. Penicillin and cephalosporin. c. Bacitracin and polymyxins d. .gentamicin and chloramphenicol
Last Answer : c. Bacitracin and polymyxins
Description : Vinca alkaloids exert antitumor activity by: A. Activating topoisomerase II to cause breaks in DNA strands B. Crosslinking DNA strands C. Inhibiting DNA mediated RNA synthesis D. Inhibiting polymerization of tubulin to form intracellular microtubules
Last Answer : D. Inhibiting polymerization of tubulin to form intracellular microtubules
Description : Translocase is an enzyme required in the process of (A) DNA replication (B) RNA synthesis (C) Initiation of protein synthesis (D) Elongation of peptides
Description : Guargum limits post-prandial glycaemia by: A. Inhibiting intestinal brush border α-glucosidases B. Slowing carbohydrate absorption from intestine C. Releasing incretins from the intestine D. Promoting uptake of glucose into skeletal muscles
Last Answer : B. Slowing carbohydrate absorption from intestin
Last Answer : Auxin hormone helps in fruit fall
Description : All of the following statements about puromycin are true except (A) It is an alanyl tRNA analogue (B) It causes premature termination of protein synthesis (C) It inhibits protein synthesis in prokaryotes (D) It inhibits protein synthesis in eukaryotes
Description : Acute pancreatitis is characterised by (A) Lack of synthesis of zymogen enzymes (B) Continuous release of zymogen enzymes into the gut (C) Premature activation of zymogen enzymes (D) Inactivation of zymogen enzymes
Description : The amino terminal of all polypeptide chain at the time of synthesis in E. coli is tagged to the amino acid residue: (A) Methionine (B) Serine (C) N-formyl methinine(D) N-formal serine
Description : The smallest unit of DNA capable of coding for the synthesis of a polypeptide is (A) Operon (B) Repressor gene (C) Cistron (D) Replicon
Description : A high plasma calcium level decreases intestinal absorption of calcium by (A) Stimulating the secretion of parathormone (B) Inhibiting the secretion of parathormone (C) Decreasing the synthesis of cholecalciferol (D) Inhibiting the secretion of thyrocalcitonin
Description : Methyl dopa decreases blood pressure by (A) Inhibiting the synthesis of catecholamines (B) Antagonising the action of aldosterone (C) Stimulating the release of renin (D) Inhibiting the breakdown of angiotensin
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 : 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 : All of the following enzymes are unique to purine nucleotide synthesis except (A) PRPP synthetase (B) PRPP glutamyl amido transferase (C) Adenylosuccinate synthetase (D) IMP dehydrogenase
Description : In the pathway of de novo synthesis of purine nucleotides, all the following are allosteric enzymes except (A) PRPP glutamyl amido transferase (B) Adenylosuccinate synthetase (C) IMP dehydrogenase (D) Adenylosuccinase
Description : The rate limiting step in catecholamine synthesis is catalysed by (A) Phenylalanine hydroxylase (B) Tyrosine hydroxylase (C) Dopa decarboxylase (D) Phenylethanolamine N-methyl transferase
Description : The enzyme regulating extramitochondrial fatty acid synthesis is (A) Thioesterase (B) Acetyl CoA carboxylase (C) Acyl transferase (D) Multi-enzyme complex
Description : Synthesis of phosphatidylinositol by transfer of inositol to CDP diacylglycerol is catalysed by the enzyme: (A) CTP phosphatidate cytidyl transferase (B) Phosphatidate phosphohydrolase (C) CDP-diacylglycerol inositol transferase (D) Choline kinase
Description : Synthesis of polyunsaturated fatty acids involves the enzyme systems: (A) Acyl transferase and hydratase (B) Desaturase and elongase (C) Ketoacyl-CoA reductase and hydratase (D) Dihydroxyacetone phosphate
Description : Acetyl CoA required for extra mitochondrial fatty acid synthesis is produced by (A) Pyruvate dehydrogenase complex (B) Citrate lyase (C) Thiolase (D) Carnitine-acyl transferase
Description : All the following statements about FSH are true except (A) It is a tropic hormone secreted by anterior pituitary (B) Its secretion is increased by gonadotropin releasing hormone (C) It acts on Sertoli cells (D) It increases the synthesis of testosterone
Description : The ‘rho’ (ρ) factor is involved (A) To increase the rate of RNA synthesis (B) In binding catabolite repressor to the promoter region (C) In proper termination of transcription (D) To allow proper initiation of transcriptide
Description : Initiation of protein synthesis requires (A) ATP (B) AMP (C) GDP (D) GTP