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

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
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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 : 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

Last Answer : Answer : A

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 : 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

Last Answer : Answer : A

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++

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

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 : Conversion of formylglycinamide ribosyl5-phosphate to formyl-glycinamide ribosyl-5-phosphate is inhibited by (A) Azaserine (B) Diazonorleucine (C) 6-Mercaptopurine (D) Mycophenolic acid

Last Answer : Answer : A

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 : 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

Last Answer : Answer : B

Ring closure of formimidoimidazole carboxamide ribosyl-5-phosphate yields the first purine nucleotide: (A) AMP (B) IMP (C) XMP (D) GMP

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

5-Phosphoribosyl-1-pyrophosphate is required for the synthesis of (A) Purine nucleotides (B) Pyrimidine nucleotides (C) Both (A) and (B) (D) None of these

Description : 5-Phosphoribosyl-1-pyrophosphate is required for the synthesis of (A) Purine nucleotides (B) Pyrimidine nucleotides (C) Both (A) and (B) (D) None of these

Last Answer : Answer : C

A common substrate of HGPRTase, APRTase and PRPP glutamyl amidotransferase is (A) Ribose 5 phosphate (B) Phosphoribosyl pyrophosphate (C) Hypoxanthine (D) Adenosine

Description : A common substrate of HGPRTase, APRTase and PRPP glutamyl amidotransferase is (A) Ribose 5 phosphate (B) Phosphoribosyl pyrophosphate (C) Hypoxanthine (D) Adenosine

Last Answer : Answer : B

In the biosynthesis of cholesterol, the step which controls the rate and locus of metabolic regulation is (A) Geranyl pyrophosphate farnesyl pyrophosphate (B) Squalene → lanosterol (C) HMG CoA → mevalonate (D) Lanosterol → 1, 4-desmethyl lanosterol

Description : In the biosynthesis of cholesterol, the step which controls the rate and locus of metabolic regulation is (A) Geranyl pyrophosphate farnesyl pyrophosphate (B) Squalene → lanosterol (C) HMG CoA → mevalonate (D) Lanosterol → 1, 4-desmethyl lanosterol

Last Answer : Answer : C

A nucleotide is formed of (a) purine, pyrimidine and phosphate (b) purine, sugar and phosphate (c) nitrogen base, sugar and phosphate (d) pyrimidine, sugar and phosphate

Description : A nucleotide is formed of (a) purine, pyrimidine and phosphate (b) purine, sugar and phosphate (c) nitrogen base, sugar and phosphate (d) pyrimidine, sugar and phosphate

Last Answer : (c) nitrogen base, sugar and phosphate

The mechanism of synthesis of DNA and RNA are similar in all the following ways except (A) They involve release of pyrophosphate from each nucleotide added (B) They require activated nucleotide precursor and Mg2+ (C) The direction of synthesis is 5’ → 3’ (D) They require a primer

Description : The mechanism of synthesis of DNA and RNA are similar in all the following ways except (A) They involve release of pyrophosphate from each nucleotide added (B) They require activated nucleotide precursor and Mg2+ (C) The direction of synthesis is 5’ → 3’ (D) They require a primer

Last Answer : Answer : A

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 : 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

Last Answer : Answer : B

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 : Salvage of purine bases is regulated by (A) Adenosine phosphoribosyl transferase (B) Hypoxanthine guanine phosphoribosyl transferase (C) Availability of PRPP (D) None of these

Last Answer : Answer : C

The enzyme required for salvage of free purine bases is (A) Adenine phosphoribosyl transferase (B) Hypoxanthine guanine phosphoribosyl transferase (C) Both (A) and (B) (D) None of these

Description : The enzyme required for salvage of free purine bases is (A) Adenine phosphoribosyl transferase (B) Hypoxanthine guanine phosphoribosyl transferase (C) Both (A) and (B) (D) None of these

Last Answer : Answer : C

The mechanism of synthesis of DNA and RNA are similar to all the following ways except (A) They involve release of pyrophosphate from each nucleotide added (B) They require activated nucleotide precursor and Mg2+ (C) The direction of synthesis is (D) They require a primer

Description : The mechanism of synthesis of DNA and RNA are similar to all the following ways except (A) They involve release of pyrophosphate from each nucleotide added (B) They require activated nucleotide precursor and Mg2+ (C) The direction of synthesis is (D) They require a primer

Last Answer : Answer : D

Which one of the following statements correctly describes eukaryotic DNA? (A) They involve release of pyrophosphate from each nucleotide precussor and Mg2+ (B) The direction of synthesis is (C) They require a primer 5’→ 3’ (D) None of these

Description : Which one of the following statements correctly describes eukaryotic DNA? (A) They involve release of pyrophosphate from each nucleotide precussor and Mg2+ (B) The direction of synthesis is (C) They require a primer 5’→ 3’ (D) None of these

Last Answer : Answer : C

Intermediate in the denovo synthesis of triacyl glycerols include all the following except (A) Fatty acyl CoA (B) CDP diacyl glycerol (C) Glycerol-3-phosphate (D) Lysophosphatidic acid

Description : Intermediate in the denovo synthesis of triacyl glycerols include all the following except (A) Fatty acyl CoA (B) CDP diacyl glycerol (C) Glycerol-3-phosphate (D) Lysophosphatidic acid

Last Answer : Answer : B

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 : 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

Last Answer : Answer : A

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

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

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 : 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

Last Answer : Answer : A

For Catecholamine biosynthesis the rate limiting enzyme is (A) DOPA decarboxylase (B) DOPAMINE β-hydroxylase (C) Tyrosine hydroxylase (D) Phenylalanine hydroxylase

Description : For Catecholamine biosynthesis the rate limiting enzyme is (A) DOPA decarboxylase (B) DOPAMINE β-hydroxylase (C) Tyrosine hydroxylase (D) Phenylalanine hydroxylase

Last Answer : Answer : C

Pyrimidine and purine nucleoside biosynthesis share a common precursor: (A) PRPP (B) Glycine (C) Fumarate (D) Alanine

Description : Pyrimidine and purine nucleoside biosynthesis share a common precursor: (A) PRPP (B) Glycine (C) Fumarate (D) Alanine

Last Answer : Answer : A

Purine biosynthesis is inhibited by (A) Aminopterin (B) Tetracyclin (C) Methotrexate (D) Chloramphenicol

Description : Purine biosynthesis is inhibited by (A) Aminopterin (B) Tetracyclin (C) Methotrexate (D) Chloramphenicol

Last Answer : Answer : A

In the biosynthesis of purine nucleotides the AMP feed back regulates (A) Adenylosuccinase (B) Adenylosuccinate synthetase (C) IMP dehydrogenase (D) HGPR Tase

Description : In the biosynthesis of purine nucleotides the AMP feed back regulates (A) Adenylosuccinase (B) Adenylosuccinate synthetase (C) IMP dehydrogenase (D) HGPR Tase

Last Answer : Answer : B

Of Which warburg’s yellow enzyme contains as a prosthetic group? (A) Thiamine pyrophosphate (B) Biotin (C) NAD+ (D) Riboflavin-5-phosphate

Description : Of Which warburg’s yellow enzyme contains as a prosthetic group? (A) Thiamine pyrophosphate (B) Biotin (C) NAD+ (D) Riboflavin-5-phosphate

Last Answer : Answer : D

An enzyme of pyrimidine nucleotide biosynthesis sensitive to allosteric regulation is (A) Aspartate transcarbamoylase (B) Dihydroorotase (C) Dihydroorotate dehydrogenase (D) Orotidylic acid decarboxylase

Description : An enzyme of pyrimidine nucleotide biosynthesis sensitive to allosteric regulation is (A) Aspartate transcarbamoylase (B) Dihydroorotase (C) Dihydroorotate dehydrogenase (D) Orotidylic acid decarboxylase

Last Answer : Answer : A

A substrate for enzymes of pyrimidine nucleotide biosynthesis is (A) Allopurinol (B) Tetracylin (C) Chloramphenicol (D) Puromycin

Description : A substrate for enzymes of pyrimidine nucleotide biosynthesis is (A) Allopurinol (B) Tetracylin (C) Chloramphenicol (D) Puromycin

Last Answer : Answer : A

The pathway of glycogen biosynthesis involves a special nucleotide of glucose. In the reaction below, NuDP stands for NuDP Glucose + glycogenn → NuDP + glycogenn+1 (A) ADP (B) GDP (C) UDP (D) CDP

Description : The pathway of glycogen biosynthesis involves a special nucleotide of glucose. In the reaction below, NuDP stands for NuDP Glucose + glycogenn → NuDP + glycogenn+1 (A) ADP (B) GDP (C) UDP (D) CDP

Last Answer : Answer : C

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 : 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

Last Answer : Answer : A

A coenzyme present in phosphorylase is (A) NAD (B) Pyridoxal phosphate (C) Thiamin pyrophosphate (D) Coenzyme A

Description : A coenzyme present in phosphorylase is (A) NAD (B) Pyridoxal phosphate (C) Thiamin pyrophosphate (D) Coenzyme A

Last Answer : Answer : B

Cocarboxylase is (A) Thiamine pyrophosphate (B) Pyridoxal phosphate (C) Biotin (D) CoA

Description : Cocarboxylase is (A) Thiamine pyrophosphate (B) Pyridoxal phosphate (C) Biotin (D) CoA

Last Answer : Answer : C

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 : 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

Last Answer : Answer : A

De novo synthesis of purine nucleotide occurs in (A) Mitochondria (B) Cytosol (C) Microsmes (D) Ribosomes

Description : De novo synthesis of purine nucleotide occurs in (A) Mitochondria (B) Cytosol (C) Microsmes (D) Ribosomes

Last Answer : Answer : B

Genetic code is (A) Collection of codon (B) Collection of amino acids (C) Collection of purine nucleotide (D) Collection of pyrimidine nucleotide

Description : Genetic code is (A) Collection of codon (B) Collection of amino acids (C) Collection of purine nucleotide (D) Collection of pyrimidine nucleotide

Last Answer : Answer : A

A purine nucleotide is (A) AMP (B) UMP (C) CMP (D) TMP

Description : A purine nucleotide is (A) AMP (B) UMP (C) CMP (D) TMP

Last Answer : Answer : A

A nucleotide consists of (A) A nitrogenous base like choline (B) Purine + pyrimidine base + sugar + phosphorous (C) Purine or pyrimidine base + sugar (D) Purine or pyrimidine base + phosphorous

Description : A nucleotide consists of (A) A nitrogenous base like choline (B) Purine + pyrimidine base + sugar + phosphorous (C) Purine or pyrimidine base + sugar (D) Purine or pyrimidine base + phosphorous

Last Answer : Answer : B

In the biosynthesis of the iron protoporphyrin, the product of the condensation between succinyl-CoA and glycine is (A) α-Amino β-ketoadipic acid (B) δ-Aminolevulinate (C) Hydroxymethylbilane (D) Uroporphyrinogen I

Description : In the biosynthesis of the iron protoporphyrin, the product of the condensation between succinyl-CoA and glycine is (A) α-Amino β-ketoadipic acid (B) δ-Aminolevulinate (C) Hydroxymethylbilane (D) Uroporphyrinogen I

Last Answer : Answer : A

A key substance in the committed step of pyrimidines biosynthesis is (A) Ribose-5-phosphate (B) Carbamoyl phosphate (C) ATP (D) Glutamine

Description : A key substance in the committed step of pyrimidines biosynthesis is (A) Ribose-5-phosphate (B) Carbamoyl phosphate (C) ATP (D) Glutamine

Last Answer : Answer : B

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 : 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

Last Answer : Answer : A

Pyrimidine biosynthesis begins with the formation from glutamine, ATP and CO2, of (A) Carbamoyl aspartate (B) Orotate (C) Carbamoyl phosphate (D) Dihydroorotate

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

In the biosynthesis of heme, condensation between succinyl CoA and glycine requires (A) NAD+ (B) FAD (C) NADH + H+ (D) B6-phosphate

Description : In the biosynthesis of heme, condensation between succinyl CoA and glycine requires (A) NAD+ (B) FAD (C) NADH + H+ (D) B6-phosphate

Last Answer : Answer : D

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

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

Last Answer : Answer : A

In the biosynthesis of triglycerides from glycerol 3-phosphate and acyl-CoA, the first intermediate formed is (A) 2-Monoacylglycerol (B) 1, 2-Diacylglycerol (C) Lysophosphatidic acid (D) Phosphatidic acid

Description : In the biosynthesis of triglycerides from glycerol 3-phosphate and acyl-CoA, the first intermediate formed is (A) 2-Monoacylglycerol (B) 1, 2-Diacylglycerol (C) Lysophosphatidic acid (D) Phosphatidic acid

Last Answer : Answer : D

Biosynthesis of Triglyceride and Lecithine both require an intermediate: (A) Monoacyl glycerol phosphate (B) Phosphatidic acid (C) Phosphatidyl ethanol amine (D) Phosphatidyl cytidylate

Description : Biosynthesis of Triglyceride and Lecithine both require an intermediate: (A) Monoacyl glycerol phosphate (B) Phosphatidic acid (C) Phosphatidyl ethanol amine (D) Phosphatidyl cytidylate

Last Answer : Answer : B

The nucleotide binding site of G-proteins is present on their (A) α-Subunit (B) β-Subunit α- and β- (C) γ-Subunit (D) δ-Subunit

Description : The nucleotide binding site of G-proteins is present on their (A) α-Subunit (B) β-Subunit α- and β- (C) γ-Subunit (D) δ-Subunit

Last Answer : Answer : A

Adenine is (a) purine (b) pyrimidine (c) nucleoside (d) nucleotide.

Description : Adenine is (a) purine (b) pyrimidine (c) nucleoside (d) nucleotide.

Last Answer : (a) purine

Uridine, present only in RNA is a (a) nucleoside (b) nucleotide (c) purine (d) pyrimidine.

Description : Uridine, present only in RNA is a (a) nucleoside (b) nucleotide (c) purine (d) pyrimidine.

Last Answer : a) nucleoside

Which one of the following contributes nitrogen atoms to both purine and pyrimidine rings? (A) Aspartate (B) Carbanoyl phosphate (C) Carbondioxide (D) Tetrahydrofolate

Description : Which one of the following contributes nitrogen atoms to both purine and pyrimidine rings? (A) Aspartate (B) Carbanoyl phosphate (C) Carbondioxide (D) Tetrahydrofolate

Last Answer : Answer : A

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 : Intestinal nucleosidases act on nucleosides and produce (A) Purine base only (B) Phosphate only (C) Sugar only (D) Purine or pyrimidine bases and sugars

Last Answer : Answer : D