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
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 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 : 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
Description : Ring closure of formimidoimidazole carboxamide ribosyl-5-phosphate yields the first purine nucleotide: (A) AMP (B) IMP (C) XMP (D) GMP
Description : A characteristic of protein synthesis in both the archaea and eukarya is A.transcription and translation are coupled B.translation is inhibited by diphtheria toxin C.proteins are synthesized from D-, ... L-, isomers of amino acids D.the initiator tRNA is charged with N-formyl- methionine
Last Answer : C.proteins are synthesized from
Description : A characteristic of protein synthesis in both the archaea and eukarya is A- transcription and translation are coupled B- translation is inhibited by diphtheria toxin C- .proteins are synthesized from D-, rather than L-, isomers of amino acids D- the initiator tRNA is charged with N-formyl-methionine
Last Answer : .proteins are synthesized from D-, rather than L-, isomers of amino acids
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 : Conversion of inosine monophosphate to xanthine monophosphate is catalysed by (A) IMP dehydrogenase (B) Formyl transferase (C) Xanthine-guanine phosphoribosyl transferase (D) Adenine phosphoribosyl transferase
Description : Hexokinase is inhibited in an allosteric manner by (A) Glucose-6-Phosphate (B) Glucose-1-Phosphate (C) Fructose-6-phosphate (D) Fructose-1, 6-biphosphate
Description : The reaction catalysed by phosphofructokinase (A) Is activated by high concentrations of ATP and citrate (B) Uses fruitose-1-phosphate as substrate (C) Is the rate-limiting reaction of the glycolytic pathway (D) Is inhibited by fructose 2, 6-bisphosphate
Last Answer : C
Description : Cytosolic carbamoyl phosphate synthetase is inhibited by (A) UTP (B) CTP (C) PRPP (D) TMP
Description : A synthetic nucleotide analogue, used in the chemotherapy of cancer and viral infections is (A) Arabinosyl cytosine (B) 4-Hydroxypyrazolopyrimidine (C) 6-Mercaptopurine (D) 6-Thioguanine
Description : A synthetic nucleotide analogue, used in organ transplantation as a suppressor of immunologic rejection of grafts is (A) Theophylline (B) Cytarabine (C) 4-Hydroxypyrazolopyrimidine (D) 6-Mercaptopurine
Description : In E. coli the chain initiating amino acid in protein synthesis is (A) N-formyl methionine(B) Methionine (C) Serine (D) Cysteine
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
Last Answer : Answer : C
Description : The first amino acid incorporated in a polypeptide in a ribosome of a bacterium is (A) N formyl methionine (B) Methionine (C) Alamine (D) Glycine
Description : The first amino acid incorporated in a polypeptide in a ribosome of a human is (A) N formyl methionine (B) Methionine (C) Phenyl alanine (D) Hydroxy lysine
Description : N10-formyl and N5N10-methenyl tetrahydrofolate contributes purine carbon atoms at position (A) 4 and 6 (B) 4 and 5 (C) 5 and 6 (D) 2 and 8
Description : Both folic acid and methyl cobalamin (vitamin B12) are required in (A) Deamination of serine (B) Deamination of threonine (C) Conversion of pyridoxal phosphate to pyridoxamine phosphate (D) Methylation of homocystein to methionine
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 : Select the drug which is used exclusively in organ transplantation and autoimmune diseases, but not in cancers: A. Cyclophosphamide B. Cyclosporine C. Methotrexate D. 6-Mercaptopurine
Last Answer : B. Cyclosporine
Description : The following anticancer drug has high emetogenic potential: A. Vincristine B. Chlorambucil C. 6-Mercaptopurine D. Cisplatin
Last Answer : D. Cisplatin
Description : Select the antimetabolite which is toxic to Leishmania but not to mammalian cells: A. Allopurinol B. Cytarabine C. 6-Mercaptopurine D. 6-Thioguanine
Last Answer : A. Allopurino
Description : Allopurinol does not inhibit the metabolism of: A. 6-Mercaptopurine B. 6-Thioguanine C. Azathioprine D. Theophylline
Last Answer : B. 6-Thioguanine
Description : Elongation of a peptide chain involves all the following except (A) mRNA (B) GTP (C) Formyl-Met-tRNA (D) Tu, TS and G factors
Description : Myeloma cells are lacking in (A) TMP synthetase (B) Formyl transferase (C) HGPRT (D) All of these
Description : For the synthesis of TMP from dump, a coenzyme is required which is (A) N10- Formyl tetrahydrofolate (B) N5- Methyl tetrahydrofolate (C) N5, N10- Methylene tetrahydrofolate (D) N5- Formimino tetrahydrofolate
Description : Tyrosine hydroxylase is inhibited by (A) Catecholamines (B) α−Methyldopa (C) Phenylalanine (D) Vanillyl mandelic acid
Description : The activity of HMG-CoA reductase is inhibited by (A) A fungal inhibitor mevastatin (B) Probucol (C) Nicotinic acid (D) Clofibrate
Description : Thioguanine differs from mercaptopurine in that: A. It is not metabolized by xanthine oxidase B. It does not cause hyperuricemia C. Its dose need not be reduced when allopurinol is given concurrently D. Both ‘A’ and ‘C’ are correc
Last Answer : D. Both ‘A’ and ‘C’ are correct
Description : Conversion of glucose to glucose-6-phosphate, the first irreversible reaction of glycolysis, is catalysed by (a) phosphofructokinase (b) aldolase (c) hexokinase (d) enolase.
Last Answer : (c) hexokinase
Description : Phosphofructokinase is allosterically inhibited by (A) Fructose-1, 6-biphosphate (B) Lactate (C) Pyruvate (D) Citrate
Description : Which of the following is present as a marker in lysosomal enzymes to direct them to their destination? (A) Glucose-6-phosphate (B) Mannose-6-phosphate (C) Galactose-6-phosphate (D) N-Acetyl neuraminic acid
Description : A substrate for the enzyme aldolase is (A) galactose-6-phosphate (B) isocitric acid (C) Glucose-1-phosphate (D) Fructose 1, 6 diphosphate
Description : I-cell disease results from absence of the following from lysosomal enzymes: (A) Signal sequence (B) Mannose-6-phosphate (C) Sialic acid (D) A serine residue
Description : Glycogen while being acted upon by active phosphorylase is converted first to (A) Glucose (B) Glucose 1-phosphate and Glycogen with 1 carbon less (C) Glucose-6-phosphate and Glycogen with 1 carbon less (D) 6-Phosphogluconic acid
Description : During translation initiation in prokaryotes, a GTP molecule is needed in (a) formation of formyl-met-tRNA (b) binding of 30S subunit of ribosome with mRNA (c) association of 30S mRNA with formyl-met- tRNA (d) association of 50S subunit of ribosome with initiation complex.
Last Answer : (c) association of 30S mRNA with formyl-met- tRNA
Description : .During translation initiation in prokaryotes, a GTP molecule is needed in (a) formation of formyl-met-tRNA (b) binding of 30S subunit of ribosome with mRNA (c) association of 30S mRNA with formyl-met- tRNA (d) association of 50S subunit of ribosome with initiation complex.
Description : Which of the following concerning the conjugation of bilirubin is correct? 1) is catalysed by a glucuronyl transferase 2) occurs in the Kupfer cells of the liver 3) is increased by valproate 4) is inhibited by rifampicin 5) is impaired in Dubin-Johnson syndrome
Last Answer : Answers-1 b - Hepatocytes. c - Enzyme inhibitor. d - Enzyme inducer. e - Conjugation is OK but excretion from the hepatocyte into the bile is impaired. (Gilbert's syndrome ... bilirubinaemia. Dubin-Johnson syndrome - bilirubin can't Depart from the hepatocyte - conjugated bilirubinaemia.)
Description : The binding of prokaryotic DNA dependent RNA polymerase to promoter sits of genes is inhibited by the antibiotic: (A) Streptomycin (B) Rifamcin (C) Aueromycin (D) Puromycin
Description : Cancer cells may become resistant to amethopterin by (A) Developing mechanisms to destroy amethopterin (B) Amplification of dihydrofolate reducatse gene (C) Mutation in the dihydrofolate reductase ... is no longer inhibited by amethopterin (D) Developing alternate pathway of thymidylate synthesis
Description : Mitochondrial protein synthesis is inhibited by (A) Cycloheximide (B) Chloramphenicol (C) Diptheria toxin (D) None of these
Description : The regulatory i gene of lac operon (A) Is inhibited by lacotse (B) Is inhibited by its own product, the repressor protein (C) Forms a regulatory protein which increases the expression of downstream structural genes (D) Is constitutively expressed
Description : Peptidyl transferase activity of 50 S ribosomal subunits is inhibited by (A) Rifampicin (B) Cycloheximide (C) Chloramphenicol (D) Erythromycin
Description : Binding of formylmehtionyl tRNA to 30 S ribosomal subunit of prokaryotes is inhibited by (A) Streptomycin (B) Chloramphenicol (C) Erythromycin (D) Mitomycin
Description : Aspartate transcarbamoylase is inhibited by (A) CTP (B) PRPP (C) ATP (D) TMP