Description : Pyrimidine biosynthesis begins with the formation from glutamine, ATP and CO2, of (A) Carbamoyl aspartate (B) Orotate (C) Carbamoyl phosphate (D) Dihydroorotate
Last Answer : Answer : C
Description : Cytosolic carbamoyl phosphate synthetase is activated by (A) Glutamine (B) PRPP (C) ATP (D) Aspartate
Last Answer : Answer : B
Description : Two nitrogen of the pyrimidines ring are obtained from (A) Glutamine and Carbamoyl-p (B) Asparate and Carbamoyl-p (C) Glutamate and NH3 (D) Glutamine and NH3
Description : The two nitrogen of the pyrimidine ring are contributed by (A) Ammonia and glycine (B) Asparate and carbamoyl phosphate (C) Glutamine and ammonia (D) Aspartate and ammonia
Description : Which of the following contributes nitrogen atoms to both purine and pyrimidine rings? (A) Aspartate (B) Carbamoyl phosphate (C) CO2 (D) Glutamine
Last Answer : Answer : A
Description : An enzyme of pyrimidine nucleotides biosynthesis regulated at the genetic level by apparently coordinate repression and derepression is (A) Carbamoyl phosphate synthetase (B) Dihydroorotate dehydrogenase (C) Thymidine kinase (D) Deoxycytidine kinase
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 : ATP is required in following reactions of urea cycle: (A) Synthesis of carbamoyl phosphate and citrulline (B) Synthesis of citrulline and argininosuccinate (C) Synthesis of argininosuccinate and arginine (D) Synthesis of carbamoyl phosphate and argininosuccinate
Description : The ‘Committed step’ in the biosynthesis of cholesterol from acetyl CoA is (A) Formation of acetoacetyl CoA from acetyl CoA (B) Formation of mevalonate from HMG CoA (C) Formation of HMG CoA from acetyl CoA and acetoacetyl CoA (D) Formation of squalene by squalene synthetase
Description : In purine biosynthesis ring closure in the molecule formyl glycinamide ribosyl-5- phosphate requires the cofactors: (A) ADP (B) NAD (C) FAD (D) ATP and Mg++
Last Answer : Answer : D
Description : CTP synthetase forms CTP from (A) CDP and inorganic phosphate (B) CDP and ATP (C) UTP and glutamine (D) UTP and glutamate
Description : Synthesis of glutamine is accompanied by the hydrolysis of (A) ATP (B) ADP (C) TPP (D) Creatin phosphate
Description : All of the following are required for synthesis of glutamine except (A) Glutamate (B) Ammonia (C) Pyridoxal phosphate (D) ATP
Description : Nucleic acids can be detected by means of their absorption maxima near 260 nm. Their absorption in this range is due to (A) Proteins (B) Purines and pyrimidines (C) Ribose (D) Deoxyribose
Description : Cytosolic and mitochondrial carbamoyl phosphate synthetase have the following similarity: (A) Both use ammonia as a substance (B) Both provide carbamoyl phosphate for urea synthesis (C) Both require N-acetylglutamate as an activator (D) Both are allosteric enzymes
Description : Identify the correct molecule which controls the biosynthesis of proteins in living organisms. (A) DNA (B) RNA (C) Purines (D) Pyrimidines
Description : A molecule of ATP contains a. Ribose But No Adenine. b. Phosphate But No Ribose. c. Adenine But No Deoxyribose. d. Deoxyribose But No Thymine.
Last Answer : b. Phosphate But No Ribose.
Description : Which one of the following is NOT part of an ATP MOLECULE? a. Phosphate group b. Cofactor c. Ribose d. Adenine
Last Answer : b. Cofactor
Description : In purine biosynthesis carbon atoms at 4 and 5 position and N at 7 position are contributed by (A) Glycine (B) Glutamine (C) Alanine (D) Threonine
Description : Hyperammonaemia type I results from congenital absence of (A) Glutamate dehydrogenase (B) Carbamoyl phosphate synthetase (C) Ornithine transcarbamoylase (D) None of these
Description : Cytosolic carbamoyl phosphate synthetase is inhibited by (A) UTP (B) CTP (C) PRPP (D) TMP
Description : De novo synthesis of pyrimidine nucleotides is regulated by (A) Carbamoyl phosphate synthetase (B) Aspartate transcarbamoylase (C) Both (A) and (B) (D) None of these
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 : An enzyme common to de novo synthesis of pyrimidine nucleotides and urea is (A) Urease (B) Carbamoyl phosphate synthetase (C) Aspartate transcarbamoylase (D) Argininosuccinase
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 : The highest energy level is present amongst the following in (A) 1, 3-Biphosphoglycerate (B) Creatine phosphate (C) Carbamoyl phosphate (D) Phosphoenol pyruvate
Description : An important finding in Hyperammonemia type II is (A) Increased serum gluatmine level (B) Enlarged liver (C) Mental retardation (D) Increased carbamoyl phosphate synthetase level
Description : Carbamoyl phosphate synthetase structure is marked by change in the presence of (A) N-Acetyl glutamate (B) N-Acetyl Aspartate (C) Neuraminic acid (D) Oxalate
Description : The metabolite which sustains urea cycle is (A) Ornithine (B) Citrulline (C) Carbamoyl phosphate (D) n-acetyl glutamate
Description : Carbamoyl phosphate required for urea synthesis is formed in (A) Cytosol (B) Mitochondria (C) Both (A) and (B) (D) None of these
Description : Transfer of the carbamoyl moiety of carbamoyl phosphate to ornithine is catalysed by a liver mitochondrial enzyme: (A) Carbamoyl phosphate synthetase (B) Ornithine transcarbamoylase (C) N-acetyl glutamate synthetase (D) N-acetyl glutamate hydrolase
Description : Control of urea cycle involves the enzyme: (A) Carbamoyl phosphate synthetase (B) Ornithine transcarbamoylase (C) Argininosuccinase (D) Arginase
Description : The enzyme carbamoyl phosphate synthetase requires (A) Mg++ (B) Ca++ (C) Na+ (D) K+
Description : A common substrate of HGPRTase, APRTase and PRPP glutamyl amidotransferase is (A) Ribose 5 phosphate (B) Phosphoribosyl pyrophosphate (C) Hypoxanthine (D) Adenosine
Description : 6-Mercapto purine inhibits the conversion of (A) IMP→ XMP (B) Ribose 5 phosphate → PRPP (C) PRPP → 5-phospho →β -D-ribosylamine (D) Glycinamide ribosyl 5-phosphate → formylglycinamide ribosyl-5-phosphate
Description : The first pentose formed in HMP shunt is (A) Ribose-5-phosphate (B) Ribulose-5-phosphate (C) Xylose-5-phosphate (D)Xylulose-5-phosphate
Description : Glucose-6-phosphate dehydrogenase is induced by (A) 6-Phosphogluconolactone (B) Glucose-6-phosphate (C) Ribose-5-phosphate (D) Insulin
Description : Pentosuria is a rare hereditary disease is characterized by increased urinary excretion of (A) L-xylulose (B) Xylitol (C) Xylulose 5-phosphate (D) Ribose 5-phosphate
Description : Xylulose-5-phosphate serves as a donar of active glycolaldehyde, the acceptor is (A) Erythrose 4-phosphate (B) Ribose 5-phosphate (C) Glyceraldehyde 3-phosphate (D) Sedoheptulose 7-phosphate
Description : In pentose phosphate pathway, D-ribulose5-phosphate is converted to D-ribose-5- phosphate by the enzyme: (A) Fumarase (B) Ketoisomerase (C) G-6-PD (D) Epimerase
Description : In RNA, apart from ribose and phosphate, all following are present except (A) Adenine (B) Guanine (C) Thymine (D) Cytosine
Description : Synthesis of GMP and IMP requires the following: (A) NH3 NAD+, ATP (B) Glutamine, NAD+, ATP (C) NH3, GTP, NADP+ (D) Glutamine, GTP, NADP+
Description : NH+ 4 aminates glutamate to form glutamine requiring ATP and (A) K+ (B) Na+ (C) Ca++ (D) Mg++
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 : In the biosynthesis of c-DNA, the joining enzyme ligase requires (A) GTP (B) ATP (C) CTP (D) UTP
Description : The enzyme aspartate transcarbamoylase of pyrimidine biosynthesis is inhibited by (A) ATP (B) ADP (C) AMP (D) CTP
Description : The 2 energy rich compounds needed for protein biosynthesis are (A) ATP and GTP (B) ATP and UTP (C) ATP and CTP (D) ATP and TTP
Description : For biosynthesis of proteins (A) Amino acids only are required (B) Amino acids and nucleic acids only are required (C) Amino acid, nucleic acids and ATP only are required (D) Amino acids, nucleic acids, ATP, GTP, enzymes and activators are required
Description : In the biosynthesis of heme, condensation between succinyl CoA and glycine requires (A) NAD+ (B) FAD (C) NADH + H+ (D) B6-phosphate
Description : The common precursor in the biosynthesis of triacylglycerol and phospholipids is (A) 1, 2-Diacylglycerol phosphate (B) 1-Acylglycerol 3-phosphate (C) Glycerol 3-phosphate (D) Dihydroxyacetone phosphate