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
Last Answer : Answer : A
Description : Conversion of formylglycinamide ribosyl5-phosphate to formyl-glycinamide ribosyl-5-phosphate is inhibited by (A) Azaserine (B) Diazonorleucine (C) 6-Mercaptopurine (D) Mycophenolic acid
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 : Ring closure of formimidoimidazole carboxamide ribosyl-5-phosphate yields the first purine nucleotide: (A) AMP (B) IMP (C) XMP (D) GMP
Last Answer : Answer : B
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 : PRPP glutamyl amidotransferase, the first enzyme uniquely committed to purine synthesis is feed back inhibited by (A) AMP (B) IMP (C) XMP (D) CMP
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 : A common substrate of HGPRTase, APRTase and PRPP glutamyl amidotransferase is (A) Ribose 5 phosphate (B) Phosphoribosyl pyrophosphate (C) Hypoxanthine (D) Adenosine
Description : An enzyme which acts as allosteric regulator and sensitive to both phosphate concentration and to the purine nucleotides is (A) PRPP synthetase (B) PRPP glutamyl midotransferase (C) HGPR Tase (D) Formyl transferase
Description : The available PRPP is used preferentially for (A) De novo synthesis of purine nucleotides (B) De novo synthesis of pyrimidine nucleotides (C) Salvage of purine bases (D) Salvage of pyrimidine bases
Last Answer : Answer : C
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 : 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 : Pyrimidine and purine nucleoside biosynthesis share a common precursor: (A) PRPP (B) Glycine (C) Fumarate (D) Alanine
Description : In EM pathway -2-phosphoglycerate is converted to (A) Phospho enol pyruvate (B) Enol pyruvate (C) Di hydroxy acetone phosphate (DHAP) (D) 1,3 bisphosphoglycerate
Last Answer : A
Description : Cytosolic carbamoyl phosphate synthetase is activated by (A) Glutamine (B) PRPP (C) ATP (D) Aspartate
Description : Cytosolic carbamoyl phosphate synthetase is inhibited by (A) UTP (B) CTP (C) PRPP (D) TMP
Description : Glucose-6-phosphate dehydrogenase is induced by (A) 6-Phosphogluconolactone (B) Glucose-6-phosphate (C) Ribose-5-phosphate (D) Insulin
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 : Rotenone inhibits the respiratory chain at (A) FMN → coenzyme Q (B) NAD → FMN (C) Coenzyme Q → cyt b (D) Cyt b → Cyt c1
Description : A key substance in the committed step of pyrimidines biosynthesis is (A) Ribose-5-phosphate (B) Carbamoyl phosphate (C) ATP (D) Glutamine
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 : 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 RNA, apart from ribose and phosphate, all following are present except (A) Adenine (B) Guanine (C) Thymine (D) Cytosine
Description : In the synthesis of glycogen from glucose the reversible step is (A) Glucose → glucose 6-phosphate (B) Glucose 6-phosphate → glucose 1-phosphate (C) Glucose 1-phosphate → UDP glucose (D) UDP glucose → glycogen
Description : In the reaction below, Nu TP stands for NuTP + glucose → Glucose 6–Phosphate + NuDP. (A) ATP (B) CTP (C) GTP (D) UTP
Description : Given that the standard free energy change (∆G°) for the hydrolysis of ATP is -7.3 K cal/mol and that for the hydrolysis of Glucose 6-phosphate is -3.3 Kcal/mol, the ∆G° for the phosphorylation of glucose is Glucose + ATP → ... -10.6 Kcal/mol (B) -7.3 Kcal/mol (C) -4.0 Kcal/mol (D) +4.0 Kcal/mol
Description : Which one of the following contributes nitrogen atoms to both purine and pyrimidine rings? (A) Aspartate (B) Carbanoyl phosphate (C) Carbondioxide (D) Tetrahydrofolate
Description : Intestinal nucleosidases act on nucleosides and produce (A) Purine base only (B) Phosphate only (C) Sugar only (D) Purine or pyrimidine bases and sugars
Description : Which of the following contributes nitrogen atoms to both purine and pyrimidine rings? (A) Aspartate (B) Carbamoyl phosphate (C) CO2 (D) Glutamine
Description : n the DNA molecule, (a) the proportion of adenine in relation to thymine varies with the organism (b) there are two strands which run anti- parallel-one in 5′ → 3′ direction and other in 3′ → ... is not always equal (d) there are two strands which run parallel in the 5′ → 3′ direction.
Last Answer : (b) there are two strands which run anti- parallel-one in 5′ → 3′ direction and other in 3′ → 5′
Description : The 4 rate limiting enzymes of gluconeogenesis are (A) Glucokinase, Pyruvate carboxylae phosphoenol pyruvate carboxykinase and glucose-6-phosphatase (B) Pyruvate carboxylase, phosphoenol ... fructokinase, pyruvate carboxylase, phosphoenol pyruvate carboxykinase and fructose 1, 6 diphosphatase
Last Answer : B
Description : In glycolytic pathway, iodacetate inhibits the activity of the enzyme: (A) Phosphotriose isomerase (B) Glyceraldehyde-3-phosphate dehydrogenase (C) Pyruvate kinase (D) Phosphofructokinase
Description : Fluoride inhibits ______ and arrests glycolysis. (A) Glyceraldehyde-3-phosphate dehydrogenase (B) Aconitase (C) Enolose (D) Succinate dehydrogenase
Last Answer : C
Description : The 5- carbon compounds produced during dark reaction of photosynthesis is (A) Ribose phosphate (B) Xylulose phosphate (C) Ribulose bis phosphate (D) Seda heptulose phosphate
Last Answer : (C) Ribulose bis phosphate
Description : Which one of the following is a non - reducing carbohydrate? (a) Maltose (b) Sucrose (c) Lactose (d) Ribose 5-phosphate
Last Answer : (b) Sucrose
Description : Polynucleotide chain of DNA contains (a) a nitrogenous base, deoxyribose sugar and phosphate group (b) a nitrogenous base, ribose sugar and phosphate group (c) deoxyribose sugar ribose sugar and phosphate group (d) a nitrogenous base and phosphate group only
Last Answer : Ans:(a)
Description : Which one of the following statements is not true of RNA? a. RNA contains the monosaccharide ribose. b. RNA is primarily a single-stranded molecule. c. RNA has a sugar-phosphate backbone. d. RNA contains five different nucleotides.
Last Answer : d. RNA contains five different nucleotides.
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 : Calcitriol inhibits the conversion of (A) Cholesterol into 7-dehydrocholesterol (B) Cholecalciferol into 1-hydroxycholecalciferol (C) Cholecalciferol into 25-hydroxycholecalciferol (D) 25-Hydroxycholecalciferol into 1,25- dihydroxycholecalciferol
Description : A chemical reaction, A → 3B, is conducted in a constant pressure vessel. Starting with pure A, the volume of the reaction mixture increases 3 times in 6 minutes. The fractional conversion is (A) 0.33 (B) 0.5 (C) 1 (D) Data insufficient, can't be predicted
Last Answer : (C) 1
Description : The enzyme glucose-6-phosphatase which catalyses the conversion of glucose 6-phosphate to glucose is not found in (A) Liver (B) Muscle (C) Intestine (D) Kidney
Description : Fatty acids can not be converted into carbohydrates in the body, as the following reaction is not possible: (A) Conversion of glucose-6-phosphate into glucose (B) Fructose 1, 6 diphosphate to ... phosphate (C) Transformation of acetyl CoA to pyruvate (D) Formation of acetyl CoA from fatty acids
Description : Fatty acids cannot be converted into carbohydrates in the body as the following reaction is not possible. (A) Conversion of glucose-6-phosphate into glucose (B) Fructose 1,6-bisphosphate to fructose- ... (C) Transformation of acetyl CoA to pyruvate (D) Formation of acetyl CoA from fatty acids
Description : Conversion of glucose to glucose-6- phosphate in human liver is by (A) Hexokinase only (B) Glucokinase only (C) Hexokinase and glucokinase (D) Glucose-6-phosphate dehydrogenase
Description : What are the activators of phospho fructo kinase?
Last Answer : AMP, Fructose-2,6-bisphosphate, Fructose-6- phosphate.
Description : What is the importance of phospho fructokinase?
Last Answer : It is the key enzyme (rate limiting enzyme) of the pathway. It is an irreversible reaction.
Description : A nucleoside is: (a) purine/pyramidine + phosphate (b) purine/pyramidine + sugar (c) Pyramidine + purine + phosphate (d) Purine + sugar + phosphate
Last Answer : Ans. ((b))