Description : Adipose tissue lacks (A) Hormone-sensitive lipase (B) Glycerol kinase (C) cAMP-dependent protein kinase (D) Glycerol-3-phosphate dehydrogenase
Last Answer : Answer : B
Description : Glucose-6-phosphatase and PEP carboxy kinase are regulated by (A) Covalent modification (B) Allosteric regulation (C) Induction and repression (D) All of these
Last Answer : Answer : C
Description : The best understood intracellular messenger is cyclic AMP (cAMP). Which of the following statement(s) concerning this intracellular messenger is/are correct? a. Intracellular cyclic AMP is constantly ... of adenylate cyclase d. cAMP is the only cyclic nucleotide active as an intracellular messenger
Last Answer : Answer: a, b The prototypic intracellular messenger is cAMP. To function as a mediator, the concentration of cAMP must change rapidly. In resting cells, cAMP is continuously being degraded by ... produce cGMP. Intracellular calcium ions also serve as second messengers in a large number of cells
Description : Vasoconstrictor effect of ADH is mediated by (A) cAMP (B) cGMP (C) Protein kinase C (D) Angiotensin II
Description : Insulin decreases the activity of (A) cAMP dependent protein kinase (B) HMG CoA-reductas (C) Phosphodiesterase (D) Acetyl CoA-carboxylase
Last Answer : Answer : A
Description : Which one of the following regulatory actions involves a reversible covalent modification of the enzyme? (A) Phosphorylation of ser-OH on the enzyme (B) Allosteric modulation (C) Competitive inhibition (D) Non-competitive inhibition
Description : Which of the following regulatory reactions involves a reversible covalent modification of an enzyme? (A) Phosphorylation of serine OH on the enzyme (B) Allosteric modulation (C) Competitive inhibition (D) Non-competitive inhibition
Description : Covalent modification of an enzyme usually involves phosphorylation / dephosphorylation of (A) Serine residue (B) Proline residue (C) Hydroxylysine residue (D) Hydroxyproline residue
Description : In biotin-containing enzymes, the biotin is bound to the enzyme by (A) An amide linkage to carboxyl group of glutamine (B) A covalent bond with CO2 (C) An amide linkage to an amino group of lysine (D) An amide linkage to α-carboxyl group of protein
Description : Regulation of haem synthesis occurs by (A) Covalent modification (B) Repression - derepression (C) Induction (D) Allosteric regulation
Description : Conversion of pepsinogen to pepsin is (A) Intra molecular rearrangement (B) Breaking of hydrogen bonds (C) Covalent modification (D) Polymerisation
Description : All the following statements about acetyl CoA carboxylase are true except: (A) It is activated by citrate (B) It is inhibited by palmitoyl CoA (C) It can undergo covalent modification (D) Its dephosphorylated form is inactive
Last Answer : Answer : D
Description : Pyruvate dehydrogenase complex is regulated by (A) Covalent modification (B) Allosteric regulation (C) Both (A) and (B) (D) None of these
Description : Regulation of some enzymes by covalent modification involves addition or removal of (A) Acetate (B) Sulphate (C) Phosphate (D) Coenzyme
Description : Activation or inactivation of certain key regulatory enzymes is accomplished by covalent modification of the amino acid: (A) Tyrosine (B) Phenylalanine (C) Lysine (D) Serine
Description : Acetyl CoA carboxylase regulates fatty acid synthesis by which of the following mechanism? (A) Allosteric regulation (B) Covalent modification (C) Induction and repression (D) All of these
Description : Give some examples of covalent modification.
Last Answer : Glycogen synthase is inactive, in the phosphorylated state, whereas glycogen phosphorylase is active when phosphorylated.
Description : What is covalent modification?
Last Answer : It means, either addition of a group to the enzyme protein by a covalent bond; or removal of a group by cleaving a covalent bond.
Description : Conversion of testosterone to estradiol requires the enzyme: (A) Aromatase (B) Dehydrogenase (C) Lyase (D) Isomerase HORMONE METABOLISM 215
Description : The antiviral action of amantadine is exerted through: A. Interaction with the viral M2 protein B. Interaction with a virus directed thymidine kinase C. Inhibition of a viral protease enzyme D. Inhibition of viral RNA mediated DNA synthesi
Last Answer : A. Interaction with the viral M2 protein
Description : Pyruvate kinase requires ______ ions for maximum activity. (A) Na+ (B) K+ (C) Ca2+ (D) Mg2+
Last Answer : B
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 : A gluconeogenic enzyme among the following is (A) Phosphofructokinase (B) Pyruvate kinase (C) Phosphoenol pyruvate carboxykinase (D) Glucokinase
Description : The first enzyme found to have isoenzymes was (A) Alkaline Phosphatase (B) Lactate dehydrogenase (C) Acid Phosphatase (D) Creatine kinase
Description : From the following myocardial infarction, the earliest serum enzyme to rise is (A) Creatine Kinase (B) GOT (C) GPT (D) LDH
Description : Which of the following serum enzyme rises in myocardial infarction: (A) Creatine kinase (B) GOT (C) LDH (D) All of these
Description : In the biosynthesis of cholesterol, the rate limiting enzyme is (A) Mevalonate kinase (B) HMG-CoA synthetase (C) HMG-CoA reductase (D) Cis-prenyl transferase
Description : Synthesis of phosphatidylinositol by transfer of inositol to CDP diacylglycerol is catalysed by the enzyme: (A) CTP phosphatidate cytidyl transferase (B) Phosphatidate phosphohydrolase (C) CDP-diacylglycerol inositol transferase (D) Choline kinase
Description : The enzyme glycerol kinase is low activity in (A) Liver (B) Kidney (C) Intestine (D) Adipose tissue
Description : Insulin has no effect on the activity of the enzyme: (A) Glycogen synthetase (B) Fructokinase (C) Pyruvate kinase (D) Pyruvate dehydrogenase
Description : An enzyme involved in gluconeogenesis is (A) Pyruvate kinase (B) Pyruvate carboxylase (C) Hexokinase (D) Phosphohexose isomerase
Description : Dietary deficiency of thiamin inhibits the activity of the enzyme: (A) Pyruvate kinase (B) Pyruvate dehydrogenase (C) Phosphofructokinase (D) Enolase
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 : The enzyme of the glycolic pathway, sensitive to inhibiton by fluoride ions is (A) Hexokinase (B) Aldolase (C) Enolase (D) Pyruvate kinase
Description : The “Primaquin sensitivity types of haemolytic anaemia has been found to relate to reduced R.B.C activity of which enzyme? (A) Pyruvate kinase deficiency (B) Glucose-6-phosphatase deficiency (C) Glucose-6-p dehydrogenase deficiency (D) Hexokinase deficiency
Last Answer : C
Description : Which one of the following is a rate limiting enzyme of gluconeogenesis? (A) Hexokinase (B) Phsophofructokinase (C) Pyruvate carboxylase (D) Pyruvate kinase
Description : The following is an enzyme required for glycolysis: (A) Pyruvate kinase (B) Pyruvate carboxylase (C) Glucose-6-phosphatose (D) Glycerokinase
Last Answer : A
Description : The following is an enzyme required for glycolysis: (A) Pyruvate kinase (B) Pyruvate carboxylase (C) Glucose-6-phosphatase (D) Glycerokinase
Description : Activated phospholipase C acts on (A) Phosphatidyl inositol-4, 5-biphosphate (B) Inositol-1, 4, 5-triphosphate (C) Protein kinase C (D) Pl-3 kinase
Description : The protein IRS-1 is phosphorylated by (A) Protein kinase A (B) Protein kinase C (C) Tyrosine kinase activity of insulin receptor (D) Tyrosine kinase activity of IGF-1 receptor
Description : All the following statements about epidermal growth factor are true except (A) It is a protein (B) It possess quaternary structure (C) Its receptor is made up of a single polypeptide chain (D) Its receptor possesses tyrosine kinase domain
Description : Protein kinase C is activated by (A) Cyclic AMP (B) Cyclic GMP (C) Diacyl glycerol (D) Inositol triphosphate
Description : Cyclic AMP binds to (A) Catalytic subunits of protein kinase (B) Regulatory subunits of protein kinase (C) Catalytic subunits of phosphorylase kinase (D) Regulatory subunits of phosphorylase kinase
Description : One of the following enzymes does not change glycogen synthase a to b. (A) Glycogen synthase kinases 3, 4, 5 (B) Ca2+ calmodulin phosphorylase kinase (C) Ca2+ calmodulin dependent protein kinase (D) Glycogen phosphorylase a
Last Answer : D
Description : Vitamin K is involved in posttranslational modification of the blood clotting factors by acting as cofactor for the enzyme: (A) Carboxylase (B) Decarboxylase (C) Hydroxylase (D) Oxidase
Description : Hormone receptors that stimulate cAMP production (A) are part of a complex of two proteins that transform the external signal into internal cAMP production (B) are proteins distinct and separate from those ... binding of the hormone (D) are not very specific and bind a number of different hormones
Description : Hormone that bind to cell surface receptor and require the second messenger camp is (A) Antidiuretic hormone (B) Cholecystokinin (C) Calcitriol (D) Gastrin
Description : Hydroxylation of 25-hydroxy cholecalciferol is promoted by (A) Cytochrome A (B) Panthyroid hormone (C) Cytochrome b (D) cAMP
Description : Hydroxylation of 25-hydroxy cholecalciferol is promoted by (A) Cytochrome - a (B) Parathyroid hormone (C) Cytochrome-b (D) CAMP
Description : Which of the following regulates lipolysis in adipocytes? (A) Activation of fatty acid synthesis mediated by CAMP (B) Glycerol phosphorylation to prevent futile esterification of fatty acids (C) ... result of hormone stimulated increases in CAMP levels (D) Activation of CAMP production by Insulin