From arachidonate, synthesis of prostaglandins is catalysed by (A) Cyclooxygenase (B) Lipoxygenase (C) Thromboxane synthase (D) Isomerase

From arachidonate, synthesis of prostaglandins is catalysed by (A) Cyclooxygenase (B) Lipoxygenase (C) Thromboxane synthase (D) Isomerase
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Cyclooxygenase-1 and –2 are responsible for (a) The synthesis of prostaglandins from arachidonate (b) The synthesis of leukotrienes from arachidonate (c) The conversion of ATP to cAMP (d) The metabolic degradation of cAMP (e) The conversion of GTP to cGMP

Description : Cyclooxygenase-1 and –2 are responsible for (a) The synthesis of prostaglandins from arachidonate (b) The synthesis of leukotrienes from arachidonate (c) The conversion of ATP to cAMP (d) The metabolic degradation of cAMP (e) The conversion of GTP to cGMP

Last Answer : Ans: A

Which of the following enzymes is ultimately responsible for the production of prostaglandins associated with inflammatory reactions? (a) Phospholipase (b) Lipoxygenase (c) Cyclooxygenase-I (d) Cyclooxygenase II (e) Xanthine oxidase

Description : Which of the following enzymes is ultimately responsible for the production of prostaglandins associated with inflammatory reactions? (a) Phospholipase (b) Lipoxygenase (c) Cyclooxygenase-I (d) Cyclooxygenase II (e) Xanthine oxidase

Last Answer : Ans: D

Inflammation is a complex tissue reaction that includes the release of cytokines, leukotrienes, prostaglandins, and peptides. Prostaglandins involved in inflammatory processes are produced from arachidonic acid by (a) Cyclooxygenase 1 (b) Cyclooxygenase 2 (c) Glutathione – S – transferase (d) Lipoxygenase (e) Phospholipase A2

Description : Inflammation is a complex tissue reaction that includes the release of cytokines, leukotrienes, prostaglandins, and peptides. Prostaglandins involved in inflammatory processes are produced from arachidonic acid by (a) ... 2 (c) Glutathione - S - transferase (d) Lipoxygenase (e) Phospholipase A2

Last Answer : Ans: B

The synthesis of heme from protophyrin III is catalysed by the enzyme: (A) ALA synthase (B) Ferroreductase (C) Ferrooxidase (D) Ferrochelatase

Description : The synthesis of heme from protophyrin III is catalysed by the enzyme: (A) ALA synthase (B) Ferroreductase (C) Ferrooxidase (D) Ferrochelatase

Last Answer : Answer : D

Non steroidal anti inflammatory drugs, such as aspirin act by inhibiting the activity of the enzyme: (A) Lipoxygenase (B) Cyclooxygenase (C) Phospholipase A2 (D) Lipoprotein lipase

Description : Non steroidal anti inflammatory drugs, such as aspirin act by inhibiting the activity of the enzyme: (A) Lipoxygenase (B) Cyclooxygenase (C) Phospholipase A2 (D) Lipoprotein lipase

Last Answer : Answer : B

Aspirin inhibits the activity of the enzyme: (A) Lipoxygenase (B) Cyclooxygenase (C) Phospholipae A1 (D) Phospholipase A2

Description : Aspirin inhibits the activity of the enzyme: (A) Lipoxygenase (B) Cyclooxygenase (C) Phospholipae A1 (D) Phospholipase A2

Last Answer : Answer : B

True statements regarding eicosanoids include which of the following? A. Prostaglandins and thromboxanes are synthesized via the cyclo-oxygenase pathway. B. The vasoconstricting, platelet-aggregating, and bronchoconstricting effects of thromboxane A 2 are balanced by the actions of prostacyclin, which produces the opposite effects. C. Leukotriene synthesis is inhibited by the action of nonsteroidal anti-inflammatory drugs (NSAIDs). D. The principal prostaglandins have a short circulation half-life and exert most of their effects locally.

Description : True statements regarding eicosanoids include which of the following? A. Prostaglandins and thromboxanes are synthesized via the cyclo-oxygenase pathway. B. The vasoconstricting, platelet-aggregating, ... prostaglandins have a short circulation half-life and exert most of their effects locally.

Last Answer : Answer: ABD DISCUSSION: The eicosanoids are a group of compounds arising from the metabolism of arachidonic acid. The prostaglandins and thromboxanes are synthesized via the cyclo-oxygenase ... effects and may be involved in the physiologic responses associated with anaphylactic and septic shock

The action of aspirin that results in its greater efficacy as an antithrombotic (anti-platelet) drug is its ability to (a) Inhibit lipoxygenase as well as cyclooxygenase (b) Selectively inhibit cyclooxygenase I (c) Inhibit leukocyte migration (d) Promote uric acid excretion (e) Acetylate cyclooxygenase

Description : The action of aspirin that results in its greater efficacy as an antithrombotic (anti-platelet) drug is its ability to (a) Inhibit lipoxygenase as well as cyclooxygenase (b) Selectively inhibit ... I (c) Inhibit leukocyte migration (d) Promote uric acid excretion (e) Acetylate cyclooxygenase

Last Answer : Ans: E

Aspirin may reduce inflammatory responses by inhibiting which of the following enzymes? A A. Cyclooxygenase B. Lipoxygenase C. Phospholipase C D. None of these

Description : Aspirin may reduce inflammatory responses by inhibiting which of the following enzymes? A A. Cyclooxygenase B. Lipoxygenase C. Phospholipase C D. None of these

Last Answer : Cyclooxygenase

Corticosteroids exert antiinflammatory action by inhibiting the following enzyme: A. Cyclooxygenase B. Lipoxygenase C. Phospholipase-A D. Phosphodiesterase

Description : Corticosteroids exert antiinflammatory action by inhibiting the following enzyme: A. Cyclooxygenase B. Lipoxygenase C. Phospholipase-A D. Phosphodiesterase

Last Answer : C. Phospholipase-A

Which of the following regarding thromboxane A2 is true? C A. It degrades basement membranes B. It is produced via the lipoxygenase pathway C. It stimulates platelet aggregation D. None of these

Description : Which of the following regarding thromboxane A2 is true? C A. It degrades basement membranes B. It is produced via the lipoxygenase pathway C. It stimulates platelet aggregation D. None of these

Last Answer : It stimulates platelet aggregation

Two molecules of acetyl-CoA condense to form acetoacetyl-CoA catalysed by (A) Thiolase (B) Kinase (C) Reductase (D) Isomerase

Description : Two molecules of acetyl-CoA condense to form acetoacetyl-CoA catalysed by (A) Thiolase (B) Kinase (C) Reductase (D) Isomerase

Last Answer : Answer : A

Conversion of the linear tetrapyrrole hydroxymethylbilane to uroporphyrinogen III (A) Occurs spontaneously (B) Catalysed by uroporphyrinogen I synthase (C) Catalysed by uroporphyrinogen III cosynthase (D) Catalysed by combined action of uroporphyrinogen I synthase and uroporphyrinogen III cosynthase

Description : Conversion of the linear tetrapyrrole hydroxymethylbilane to uroporphyrinogen III (A) Occurs spontaneously (B) Catalysed by uroporphyrinogen I synthase (C) Catalysed by uroporphyrinogen III cosynthase (D) Catalysed by combined action of uroporphyrinogen I synthase and uroporphyrinogen III cosynthase

Last Answer : Answer : D

Which of the following statement(s) is/are correct concerning the immunoinflammatory response to shock? a. The anaphylactoxins, C3a and C5a, are products of activation of only the classical pathway of the compliment cascade b. Eicosanoids, such as prostaglandins are stored in platelets and endothelial cells and released in response to inflammatory stimuli c. Thromboxane and PGI2 have similar effects d. Platelet-activating factor can be released by both circulating and fixed tissue cells

Description : Which of the following statement(s) is/are correct concerning the immunoinflammatory response to shock? a. The anaphylactoxins, C3a and C5a, are products of activation of only the classical pathway ... effects d. Platelet-activating factor can be released by both circulating and fixed tissue cells

Last Answer : Answer: d Inflammatory mediators have recently been recognized as playing a significant role in the clinical manifestations and progression of shock and the development ... increased pulmonary vascular resistance, bronchoconstriction, peripheral vasodilatation, and increased vascular permeability

Dilatation of the peripheral arterial blood vessels can be caused by: a. thromboxane A2 b. adenosine diphosphatc. endothelin d. prostaglandins e

Description : Dilatation of the peripheral arterial blood vessels can be caused by: a. thromboxane A2 b. adenosine diphosphate c. endothelin d. prostaglandins

Last Answer : prostaglandins

The following are true about chemicals involved in allergic reaction: a. thromboxane -leukocyte activation b. prostaglandin-2 - vasodilatation c. platelet-activating factor - leukocyte activation d. heparin - augments inactivation of prostaglandins

Description : The following are true about chemicals involved in allergic reaction: a. thromboxane -leukocyte activation b. prostaglandin-2 - vasodilatation c. platelet-activating factor - leukocyte activation d. heparin - augments inactivation of prostaglandins

Last Answer : prostaglandin-2 - vasodilatation

In mammals, synthesis of mRNA is catalysed by (A) RNA polymerase I (B) RNA polymerase II (C) RNA polymerase III(D) RNA polymerase IV

Description : In mammals, synthesis of mRNA is catalysed by (A) RNA polymerase I (B) RNA polymerase II (C) RNA polymerase III(D) RNA polymerase IV

Last Answer : Answer : B

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

The rate limiting step in catecholamine synthesis is catalysed by (A) Phenylalanine hydroxylase (B) Tyrosine hydroxylase (C) Dopa decarboxylase (D) Phenylethanolamine N-methyl transferase

Description : The rate limiting step in catecholamine synthesis is catalysed by (A) Phenylalanine hydroxylase (B) Tyrosine hydroxylase (C) Dopa decarboxylase (D) Phenylethanolamine N-methyl transferase

Last Answer : Answer : B

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 : 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

Last Answer : Answer : C

In gluconeogensis, an allosteric activator required in the synthesis of oxaloacetate from bicarbonate and pyruvate, which is catalysed by the enzyme pyruvate carboxylase is (A) Acetyl CoA (B) Succinate (C) Isocitrate (D) Citrate

Description : In gluconeogensis, an allosteric activator required in the synthesis of oxaloacetate from bicarbonate and pyruvate, which is catalysed by the enzyme pyruvate carboxylase is (A) Acetyl CoA (B) Succinate (C) Isocitrate (D) Citrate

Last Answer : Answer : A

De novo synthesis of fatty acids is catalysed by a multi-enzyme complex which contains (A) One-SH group (B) Two-SH groups (C) Three-SH groups (D) Four-SH groups

Description : De novo synthesis of fatty acids is catalysed by a multi-enzyme complex which contains (A) One-SH group (B) Two-SH groups (C) Three-SH groups (D) Four-SH groups

Last Answer : Answer : D

A cup of strong coffee would be expected to (A) Interfere with synthesis of prostaglandins (B) Decrease the effects of Glucagon (C) Enhance the effects of epinephrine (D) Provide the vitamin nicotinic acid

Description : A cup of strong coffee would be expected to (A) Interfere with synthesis of prostaglandins (B) Decrease the effects of Glucagon (C) Enhance the effects of epinephrine (D) Provide the vitamin nicotinic acid

Last Answer : Answer : C

Aspirin blocks the synthesis of (A) Prostaglandins only (B) Prostacyclins only (C) Thromboxanes only (D) All of these

Description : Aspirin blocks the synthesis of (A) Prostaglandins only (B) Prostacyclins only (C) Thromboxanes only (D) All of these

Last Answer : Answer : D

A cup of strong coffee would be expected to (A) Interfere with the synthesis of prostaglandins (B) Decrease the effect of glucagon (C) Enhance the effect of epinephrine (D) Provide the vitamin nicotinic acid

Description : A cup of strong coffee would be expected to (A) Interfere with the synthesis of prostaglandins (B) Decrease the effect of glucagon (C) Enhance the effect of epinephrine (D) Provide the vitamin nicotinic acid

Last Answer : Answer : C

Cyclo-oxygenase is involved in the synthesis of (A) Prostaglandins (B) Thromboxanes (C) Both (A) and (B) (D) None of these

Description : Cyclo-oxygenase is involved in the synthesis of (A) Prostaglandins (B) Thromboxanes (C) Both (A) and (B) (D) None of these

Last Answer : Answer : C

Lipo-oxygenase is required for the synthesis of (A) Prostaglandins (B) Leukotrienes (C) Thromboxanes (D) All of these

Description : Lipo-oxygenase is required for the synthesis of (A) Prostaglandins (B) Leukotrienes (C) Thromboxanes (D) All of these

Last Answer : Answer : B

Synthesis of prostaglandins is inhibited by (A) Glucocorticoids (B) Aspirin (C) Indomethacin (D) All of these

Description : Synthesis of prostaglandins is inhibited by (A) Glucocorticoids (B) Aspirin (C) Indomethacin (D) All of these

Last Answer : Answer : D

Anti-inflammatory corticosteroids inhibit the synthesis of (A) Leukotrienes (B) Prostaglandins (C) Thromboxanes (D) All of these

Description : Anti-inflammatory corticosteroids inhibit the synthesis of (A) Leukotrienes (B) Prostaglandins (C) Thromboxanes (D) All of these

Last Answer : Answer : D

For synthesis of prostaglandins, the essential fatty acids give rise to a fatty acid containing (A) 12 carbon atoms (B) 16 carbon atoms (C) 20 carbon atoms (D) 24 carbon atoms

Description : For synthesis of prostaglandins, the essential fatty acids give rise to a fatty acid containing (A) 12 carbon atoms (B) 16 carbon atoms (C) 20 carbon atoms (D) 24 carbon atoms

Last Answer : Answer : C

A patient who has been taking quantities of aspirin might show increased post operative bleeding because aspirin inhibits:** A. Synthesis of thromboxane A2 and prevents platelet aggregation B. Synthesis of prostacyclin and prevents platelet aggregation C. Synthesis of prostaglandin and prevents production of blood platelets D. Thrombin and prevents formation of the fibrin network E. Increase the absorption of vitamin K and prevents synthesis of blood clotting factors

Description : A patient who has been taking quantities of aspirin might show increased post operative bleeding because aspirin inhibits:** A. Synthesis of thromboxane A2 and prevents platelet aggregation B. ... network E. Increase the absorption of vitamin K and prevents synthesis of blood clotting factors

Last Answer : A. Synthesis of thromboxane A2 and prevents platelet aggregation

Choose the correct statement about ticlopidine: A. It blocks GPIIb/IIIa receptors on platelet membrane B. It prevents ADP mediated platelet adenylylcyclase inhibition C. It inhibits thromboxane A2 synthesis in platelets D. It does not prolong bleeding time

Description : Choose the correct statement about ticlopidine: A. It blocks GPIIb/IIIa receptors on platelet membrane B. It prevents ADP mediated platelet adenylylcyclase inhibition C. It inhibits thromboxane A2 synthesis in platelets D. It does not prolong bleeding time

Last Answer : B. It prevents ADP mediated platelet adenylylcyclase inhibition

Inhibition of thromboxane synthesis by aspirin in platelets lasts for 5-7 days because: A. Aspirin persists in the body for 5-7 days B. Aspirin induced depletion of arachidonic acid lasts 5-7 days C. Regeneration of aspirin inhibited cyclooxygenase takes 5-7 days D. Platelets cannot generate fresh thromboxane synthetase and their turnover time is 5-7 days

Description : Inhibition of thromboxane synthesis by aspirin in platelets lasts for 5-7 days because: A. Aspirin persists in the body for 5-7 days B. Aspirin induced depletion of arachidonic acid lasts 5-7 ... 5-7 days D. Platelets cannot generate fresh thromboxane synthetase and their turnover time is 5-7 days

Last Answer : D. Platelets cannot generate fresh thromboxane synthetase and their turnover time is 5-7 days

Aspirin prolongs bleeding time by inhibiting the synthesis of: A. Clotting factors in liver B. Prostacyclin in vascular endothelium C. Cyclic AMP in platelets D. Thromboxane A2 in platelets

Description : Aspirin prolongs bleeding time by inhibiting the synthesis of: A. Clotting factors in liver B. Prostacyclin in vascular endothelium C. Cyclic AMP in platelets D. Thromboxane A2 in platelets

Last Answer : D. Thromboxane A2 in platelets

Selective inhibition of thromboxane A2 synthesis by low dose aspirin therapy might retard the progression of: A. Pregnancy induced hypertension B. Steroid induced hypertension C. Renal hypertension D. Malignant hypertension

Description : Selective inhibition of thromboxane A2 synthesis by low dose aspirin therapy might retard the progression of: A. Pregnancy induced hypertension B. Steroid induced hypertension C. Renal hypertension D. Malignant hypertension

Last Answer : A. Pregnancy induced hypertension

Low doses of aspirin prolong bleeding time by selectively inhibiting synthesis of the following mediator in the platelets: A. Thromboxane A2 B. 5-Hydroxytryptamine C. Platelet activating factor D. Prostacyclin

Description : Low doses of aspirin prolong bleeding time by selectively inhibiting synthesis of the following mediator in the platelets: A. Thromboxane A2 B. 5-Hydroxytryptamine C. Platelet activating factor D. Prostacyclin

Last Answer : A. Thromboxane

.Which of these is not an important component of initiation of parturition in humans? (a) Release of oxytocin (b) Release of prolactin (c) Increase in estrogen and progesterone ratio (d) Synthesis of prostaglandins

Description : .Which of these is not an important component of initiation of parturition in humans? (a) Release of oxytocin (b) Release of prolactin (c) Increase in estrogen and progesterone ratio (d) Synthesis of prostaglandins

Last Answer : b) Release of prolactin

Leukotrienes: 1) Are formed from the cyclooxygenase pathway 2) Are synthesized by fibroblasts 3) Decrease vascular permeability 4) Leukotriene D4 has been identified as SRS-A which causes bronchial wall smooth muscle relaxation 5) Stimulate mucus secretion

Description : Leukotrienes: 1) Are formed from the cyclooxygenase pathway 2) Are synthesized by fibroblasts 3) Decrease vascular permeability 4) Leukotriene D4 has been identified as SRS-A which causes bronchial wall smooth muscle relaxation 5) Stimulate mucus secretion

Last Answer : Answers-5 Leukotrienes are synthesized by leucocytes.They are mediators of allergic reaction. They increase vascular permeability and attract neutrophils and eosinophils to inflammatory sites. ... stimulate mucus production, an important consideration in the pathophysiology of bronchial asthma.

Glutathione is a constituent of (A) Leukotriene A4 (B) Thromboxane A1 (C) Leukotriene C4 (D) None of these

Description : Glutathione is a constituent of (A) Leukotriene A4 (B) Thromboxane A1 (C) Leukotriene C4 (D) None of these

Last Answer : Answer : C

What is the effect of thromboxane?

Description : What is the effect of thromboxane? 

Last Answer : Thromboxane (TXA2) is the main PG produced by platelets. The major effects are vasoconstriction and platelet aggregation. Prostacyclin and thromboxane are opposing in activity.

Conversion of testosterone to estradiol requires the enzyme: (A) Aromatase (B) Dehydrogenase (C) Lyase (D) Isomerase HORMONE METABOLISM 215

Description : Conversion of testosterone to estradiol requires the enzyme: (A) Aromatase (B) Dehydrogenase (C) Lyase (D) Isomerase HORMONE METABOLISM 215

Last Answer : Answer : A

The enzyme catalyzing conversion of androstenedione to testosterone is a (A) Oxygenase (B) Dehydrogenase (C) Isomerase (D) Decarboxylase

Description : The enzyme catalyzing conversion of androstenedione to testosterone is a (A) Oxygenase (B) Dehydrogenase (C) Isomerase (D) Decarboxylase

Last Answer : Answer : B

3-β-Hydroxysteroid dehydrogenase and ∆5,4 isomerase catalyse the conversion of the weak androgen DHEA to (A) Androstenedione (B) Testosterone (C) Progesterone (D) Estrone

Description : 3-β-Hydroxysteroid dehydrogenase and ∆5,4 isomerase catalyse the conversion of the weak androgen DHEA to (A) Androstenedione (B) Testosterone (C) Progesterone (D) Estrone

Last Answer : Answer : A

In the biosynthesis of cortiol, the sequence of enzymes involved is (A) Hydroxylase–dehydrogenase + isomerase – hydroxylase (B) Dehydrogenase–hydroxylase–isomerase (C) Hydroxylase–lyase–dehydrogenase isomerase (D) Isomerase–lyase–hydroxylase–dehydrogenase

Description : In the biosynthesis of cortiol, the sequence of enzymes involved is (A) Hydroxylase–dehydrogenase + isomerase – hydroxylase (B) Dehydrogenase–hydroxylase–isomerase (C) Hydroxylase–lyase–dehydrogenase isomerase (D) Isomerase–lyase–hydroxylase–dehydrogenase

Last Answer : Answer : A

Urease is a (A) Lyase (B) Ligase (C) Isomerase (D) Hydrolase

Description : Urease is a (A) Lyase (B) Ligase (C) Isomerase (D) Hydrolase

Last Answer : Answer : D

Pyruvate dehydrogenase is a/an (A) Isomerase (B) Lyase (C) Ligase (D) Oxido reductase

Description : Pyruvate dehydrogenase is a/an (A) Isomerase (B) Lyase (C) Ligase (D) Oxido reductase

Last Answer : Answer : D

Glucose-6-phosphate is an allosteric inhibitor of (A) Glucokinase (B) Hexokinase (C) Phosphohexose isomerase (D) None of these

Description : Glucose-6-phosphate is an allosteric inhibitor of (A) Glucokinase (B) Hexokinase (C) Phosphohexose isomerase (D) None of these

Last Answer : Answer : B

Which of the following is an allosteric enzyme? (A) Phosphohexose isomerase (B) Phosphotriose isomerase (C) Lactate dehydrogenase (D) Phosphofructokinase

Description : Which of the following is an allosteric enzyme? (A) Phosphohexose isomerase (B) Phosphotriose isomerase (C) Lactate dehydrogenase (D) Phosphofructokinase

Last Answer : Answer : D

In biosynthesis of cholesterol triparanol inhibits the activity of the enzyme: (A) ∆24 Reductase (B) Oxidosqualene-lanosterol cyclase (C) Isomerase (D) Squalene epoxidase ENZYMES 155

Description : In biosynthesis of cholesterol triparanol inhibits the activity of the enzyme: (A) ∆24 Reductase (B) Oxidosqualene-lanosterol cyclase (C) Isomerase (D) Squalene epoxidase ENZYMES 155

Last Answer : Answer : A