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
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
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 : 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 : 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
Last Answer : Answer : D
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 : 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 : 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 : 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 : A common substrate of HGPRTase, APRTase and PRPP glutamyl amidotransferase is (A) Ribose 5 phosphate (B) Phosphoribosyl pyrophosphate (C) Hypoxanthine (D) Adenosine
Description : All of the following occur in orotic aciduria except (A) Increased synthesis of pyrimidine nucleotides (B) Increased excretion of orotic acid in urine (C) Decreased synthesis of cytidine triphosphate (D) Retardation of growth
Description : During de novo synthesis of pyrimidine nucleotides, the first ring compound to be formed is (A) Carbamoyl aspartic acid (B) Dihydro-orotic acid (C) Orotic acid (D) Orotidine monophosphate
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 : De novo synthesis of pyrimidine nucleotides occurs in (A) Mitochondria (B) Cytosol (C) Microsomes (D) Ribosomes
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 : For de novo synthesis of purine nucleotides, aspartate provides (A) Nitrogen 1 (B) Nitrogen 3 (C) Nitrogen 7 (D) Nitrogen 9
Description : For de novo synthesis of purine nucleotides, glycine provides (A) One nitrogen atom (B) One nitrogen and one carbon atom (C) Two carbon atoms (D) One nitrogen and two carbon atoms
Description : The nitrogen atoms for de novo synthesis of purine nucleotides are provided by (A) Aspartate and glutamate (B) Aspartate and glycine (C) Aspartate, glutamine and glycine (D) Aspartate, glutamate and glycine
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 : 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 of the following contributes nitrogen atoms to both purine and pyrimidine rings? (A) Aspartate (B) Carbamoyl phosphate (C) CO2 (D) Glutamine
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 : 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 : Which one of the following causes frame shift mutation? (A) Transition (B) Transversion (C) Deletion (D) Substitution of purine to pyrimidine
Description : In DNA, genetic information is located in (A) Purine bases (B) Pyrimidine bases (C) Purine and pyrimidine bases (D) sugar
Description : The structural stability of the double helix of DNA is as cribbed largely to (A) Hydrogen bonding between adjacent purine bases (B) Hydrophobic bonding between staked purine and ... Hydrogen bonding between adjacent pyrimidine bases (E) Hydrogen bonding between purine and pyrimidine bases
Description : Ultraviolet light can damage a DNA strand causing (A) Two adjacent purine residue to form a covalently bounded dimer (B) Two adjacent pyrimidine residues to form covalently bonded dimer (C) Disruption of phosphodiesterase linkage (D) Disruption of non-covalent linkage
Description : Genetic code is (A) Collection of codon (B) Collection of amino acids (C) Collection of purine nucleotide (D) Collection of pyrimidine nucleotide
Description : Gout is a metabolic disorder of catabolism of (A) Pyrimidine (B) Purine (C) Alanine (D) Phenylalanine
Description : Pyrimidine and purine nucleoside biosynthesis share a common precursor: (A) PRPP (B) Glycine (C) Fumarate (D) Alanine
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 : In RNA molecule guanine content does not necessarily equal its cytosine content nor does its adenine content necessarily equal its uracil content since it is a (A) Single strand molecule ( ... stranded molecule (C) Double stranded helical molecule (D) Polymer of purine and pyrimidine ribonucleotides
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
Description : A nucleoside consists of (A) Nitrogenous base (B) Purine or pyrimidine base + sugar (C) Purine or pyrimidine base + phosphorous (D) Purine + pyrimidine base + sugar + phosphorous
Description : All mammalian steroid hormones are formed from (A) Purine (B) Pyrimidine (C) Cholesterol (D) Pyrrole
Description : Thiamine is (A) Water-soluble vitamin (B) Fat soluble vitamin (C) Purine base (D) Pyrimidine base
Description : Thymine is (A) Water soluble vitamin (B) Fat soluble vitamin (C) Purine base (D) Pyrimidine base
Description : Vitamin B12 has a complex ring structure (corrin ring) consisting of four (A) Purine rings (B) Pyrimidine rings (C) Pyrrole rings (D) Pteridine rings
Description : The common features of introns include all the following except (A) The base sequence begins with GU (B) The base sequence ends with AG (C) The terminal AG sequence is preceded by a purine rich tract of ten nucleotides (D) An adenosine residue in branch site participates in splicing
Description : In the biosynthesis of purine nucleotides the AMP feed back regulates (A) Adenylosuccinase (B) Adenylosuccinate synthetase (C) IMP dehydrogenase (D) HGPR Tase
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
Description : Nucleotides required for the synthesis of nucleic acids can be obtained from (A) Dietary nucleic acids and nucleotides (B) De novo synthesis (C) Salvage of pre-existing bases and nucleosides (D) De novo synthesis and salvage
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
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
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 : 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 : Similarity in DNA and RNA is that (a) both are polymer of nucleotides (b) both have similar pyrimidine (c) both have similar sugar (d) both are genetic material.
Last Answer : (b) both have similar pyrimidine
Last Answer : both are polymer of nucleotides
Description : Difference between purine and pyrimidine. -Biology
Last Answer : answer: