A substance unrelated to substrate but capable of reversibly changing activity of enzyme by binding to a site other than active site is called (a) Competitive inhibitor (b) Non-competitive inhibitor (c) Catalytic inhibitor (d) Allosteric modulator/inhibitor

A substance unrelated to substrate but capable of reversibly changing activity of enzyme by binding to a site other than active site is called (a) Competitive inhibitor (b) Non-competitive inhibitor (c) Catalytic inhibitor (d) Allosteric modulator/inhibitor
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Ans. ((d))
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An allosteric enzyme influences the enzyme activity by (A) Competiting for the catalytic site with the substrate (B) Changing the specificity of the enzyme for the substrate (C) Changing the conformation of the enzyme by binding to a site other than catalytic site (D) Changing the nature of the products formed

Description : An allosteric enzyme influences the enzyme activity by (A) Competiting for the catalytic site with the substrate (B) Changing the specificity of the enzyme for the substrate (C) Changing the conformation ... binding to a site other than catalytic site (D) Changing the nature of the products formed

Last Answer : Answer : C

Which one of the following statements regarding enzyme inhibition is correct? (a) Competitive inhibition is seen when a substrate competes with an enzyme for binding to an inhibitor protein. (b) Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme. (c) Non-competitive inhibition of an enzyme can be overcome by adding large amount of substrate. (d) Non-competitive inhibitors often bind to the enzyme irreversibly.

Description : Which one of the following statements regarding enzyme inhibition is correct? (a) Competitive inhibition is seen when a substrate competes with an enzyme for binding to an inhibitor protein. (b ... large amount of substrate. (d) Non-competitive inhibitors often bind to the enzyme irreversibly.

Last Answer : (b) Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme

Which one of the following statements is incorrect? (a) The competitive inhibitor does not affect the rate of breakdown of the enzyme-substrate complex. (b) The presence of the competitive inhibitor decreases the Km of the enzyme for the substrate. (c) A competitive inhibitor reacts reversibly with the enzyme to form an enzyme-inhibitor complex. (d) In competitive inhibition, the inhibitor molecule is not chemically changed by the enzyme.

Description : Which one of the following statements is incorrect? (a) The competitive inhibitor does not affect the rate of breakdown of the enzyme-substrate complex. (b) The presence of the competitive inhibitor ... . (d) In competitive inhibition, the inhibitor molecule is not chemically changed by the enzyme.

Last Answer : (b) The presence of the competitive inhibitor decreases the Km of the enzyme for the substrate

The shape of an enzyme and consequently its activity can be reversibly altered from moment to moment by (A) Heat (B) Amino acid substrate (C) Allosteric subunits (D) Sulfur substitutions

Description : The shape of an enzyme and consequently its activity can be reversibly altered from moment to moment by (A) Heat (B) Amino acid substrate (C) Allosteric subunits (D) Sulfur substitutions

Last Answer : Answer : C

Which inactivates an enzyme by occupying its active site? (A) Competitive inhibitor (B) Allosteric inhibitor (C) Non-competitive inhibitor (D) All of these

Description : Which inactivates an enzyme by occupying its active site? (A) Competitive inhibitor (B) Allosteric inhibitor (C) Non-competitive inhibitor (D) All of these

Last Answer : Answer : A

Select the option which is not correct with respect to enzyme action. (a) Substrate binds with enzyme at its active site. (b) Addition of lot of succinate does not reverse the inhibition of succinic dehydrogenase by malonate. (c) A non-competitive inhibitor binds the enzyme at a site distinct from that which binds the substrate. (d) Malonate is a competitive inhibitor of succinic dehydrogenase.

Description : Select the option which is not correct with respect to enzyme action. (a) Substrate binds with enzyme at its active site. (b) Addition of lot of succinate does not reverse the inhibition ... from that which binds the substrate. (d) Malonate is a competitive inhibitor of succinic dehydrogenase.

Last Answer : (b) Addition of lot of succinate does not reverse the inhibition of succinic dehydrogenase by malonate.

Enzyme inhibition caused by a substance resembling substrate molecule is (A) Competitive inhibition (B) Non-competitive inhibition (C) Feedback inhibition (D) Allosteric inhibition

Description : Enzyme inhibition caused by a substance resembling substrate molecule is (A) Competitive inhibition (B) Non-competitive inhibition (C) Feedback inhibition (D) Allosteric inhibition

Last Answer : Answer : A

A competitive inhibitor of an enzyme has which of the following properties? (A) It is frequently a feedback inhibitor (B) It becomes covalently attached to an enzyme (C) It decreases the Vmax (D) It interferes with substrate binding to the enzyme

Description : A competitive inhibitor of an enzyme has which of the following properties? (A) It is frequently a feedback inhibitor (B) It becomes covalently attached to an enzyme (C) It decreases the Vmax (D) It interferes with substrate binding to the enzyme

Last Answer : Answer : D

In reversible non-competitive enzyme activity inhibition (A) Inhibitor bears structural resemblance to substrate (B) Inhibitor lowers the maximum velocity attainable with a given amount of enzyme (C) Km is increased (D) Km is decreased

Description : In reversible non-competitive enzyme activity inhibition (A) Inhibitor bears structural resemblance to substrate (B) Inhibitor lowers the maximum velocity attainable with a given amount of enzyme (C) Km is increased (D) Km is decreased

Last Answer : Answer : B

In competitive enzyme activity inhibition (A) The structure of inhibitor generally resembles that of the substrate (B) Inhibitor decreases apparent Km (C) Km remains unaffective (E) Inhibitor decreases Vmax without affecting Km

Description : In competitive enzyme activity inhibition (A) The structure of inhibitor generally resembles that of the substrate (B) Inhibitor decreases apparent Km (C) Km remains unaffective (E) Inhibitor decreases Vmax without affecting Km

Last Answer : Answer : A

Competitive inhibition can be relieved by raising the (A) Enzyme concentration (B) Substrate concentration (C) Inhibitor concentration (D) None of these

Description : Competitive inhibition can be relieved by raising the (A) Enzyme concentration (B) Substrate concentration (C) Inhibitor concentration (D) None of these

Last Answer : Answer : B

In competitive inhibition, the inhibitor (A) Competes with the enzyme (B) Irreversibly binds with the enzyme (C) Binds with the substrate (D) Competes with the substrate

Description : In competitive inhibition, the inhibitor (A) Competes with the enzyme (B) Irreversibly binds with the enzyme (C) Binds with the substrate (D) Competes with the substrate

Last Answer : Answer : D

What is it called when an enzyme is blocked at its active site so the normal substrate can't bind? a. Competitive Inhibition b. Feedback Inhibition c. Noncompetitive Inhibition d. Pathway Modulation

Description : What is it called when an enzyme is blocked at its active site so the normal substrate can't bind? a. Competitive Inhibition b. Feedback Inhibition c. Noncompetitive Inhibition d. Pathway Modulation

Last Answer : a. Competitive Inhibition

ATP is a co-substrate as well as an allosteric inhibitor of (A) Phosphofructokinase (B) Hexokinase (C) Glucokinase (D) None of these

Description : ATP is a co-substrate as well as an allosteric inhibitor of (A) Phosphofructokinase (B) Hexokinase (C) Glucokinase (D) None of these

Last Answer : Answer : A

In non competitive enzyme activity inhibition, inhibitor (A) Increases Km (B) Decreases Km (C) Does not effect Km (D) Increases Km

Description : In non competitive enzyme activity inhibition, inhibitor (A) Increases Km (B) Decreases Km (C) Does not effect Km (D) Increases Km

Last Answer : Answer : C

Allosteric inhibition (A) Makes active site unifit for substrate (B) Controls excess formation and end product (C) Both (A) and (B) (D) None of these

Description : Allosteric inhibition (A) Makes active site unifit for substrate (B) Controls excess formation and end product (C) Both (A) and (B) (D) None of these

Last Answer : Answer : C

Fischer’s ‘lock and key’ model of the enzyme action implies that (A) The active site is complementary in shape to that of substance only after interaction. (B) The active site is complementary in shape to that of substance (C) Substrates change conformation prior to active site interaction (D) The active site is flexible and adjusts to substrate

Description : Fischer's lock and key' model of the enzyme action implies that (A) The active site is complementary in shape to that of substance only after interaction. (B) The active site is ... change conformation prior to active site interaction (D) The active site is flexible and adjusts to substrate

Last Answer : Answer : B

Which one of the following statements is not characteristic of allosteric enzymes? (A) They frequently catalyze a committed step early in a metabolic pathway (B) They are often composed of subunits (C) They follow Michaelis-Menten kinetics (D) They frequently show cooperativity for substrate binding

Description : Which one of the following statements is not characteristic of allosteric enzymes? (A) They frequently catalyze a committed step early in a metabolic pathway (B) They are often composed of subunits (C) They follow Michaelis-Menten kinetics (D) They frequently show cooperativity for substrate binding

Last Answer : Answer : C

A sigmoidal plot of substrate concentration ([S]) verses reaction velocity (V) may indicate (A) Michaelis-Menten kinetics (B) Co-operative binding (C) Competitive inhibition (D) Non-competitive inhibition

Description : A sigmoidal plot of substrate concentration ([S]) verses reaction velocity (V) may indicate (A) Michaelis-Menten kinetics (B) Co-operative binding (C) Competitive inhibition (D) Non-competitive inhibition

Last Answer : Answer : B

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 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

Last Answer : Answer : A

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 : 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

Last Answer : Answer : A

Regulator gene controls chemical synthesis (Operon concept) by (a) Inhibiting transcription of mRNA (b) Inhibiting enzymes (c) Inhibiting passage of mRNA (d) Inhibiting substrate enzyme reaction

Description : Regulator gene controls chemical synthesis (Operon concept) by (a) Inhibiting transcription of mRNA (b) Inhibiting enzymes (c) Inhibiting passage of mRNA (d) Inhibiting substrate enzyme reaction

Last Answer : Ans. ((a))

An allosteric enzyme is generally inhibited by (A) Initial substrate of the pathway (B) Substrate analogues (C) Product of the reaction catalysed by allosteric enzyme (D) Product of the pathway

Description : An allosteric enzyme is generally inhibited by (A) Initial substrate of the pathway (B) Substrate analogues (C) Product of the reaction catalysed by allosteric enzyme (D) Product of the pathway

Last Answer : Answer : D

Which of the following statements about an enzyme exhibiting allosteric kinetics with cooperative interaction is false? (A) A plot of V-Vk [s] has a sigmaidal shape (B) An inhibitor may increase the apparent Km (C) Line weaver Bnrk plot is useful for determining Km and Vmax (D) Removal of allosteric inhibitor may result in hyperbolic V-S [s] plot

Description : Which of the following statements about an enzyme exhibiting allosteric kinetics with cooperative interaction is false? (A) A plot of V-Vk [s] has a sigmaidal shape (B) An inhibitor may increase the ... Km and Vmax (D) Removal of allosteric inhibitor may result in hyperbolic V-S [s] plot

Last Answer : Answer : D

In reversible non-competitive enzyme activity inhibition (A) Vmax is increased (B) Km is increased (C) Km is decreased (D) Concentration of active enzyme is reduced

Description : In reversible non-competitive enzyme activity inhibition (A) Vmax is increased (B) Km is increased (C) Km is decreased (D) Concentration of active enzyme is reduced

Last Answer : Answer : D

A catalyst loses its activity due to (A) Loss in surface area of the active component (B) Agglomeration of metal particles caused by thermal sintering of the solid surface (C) Covering of the catalytic active sites by a foreign substance (D) All (A), (B) and (C)

Description : A catalyst loses its activity due to (A) Loss in surface area of the active component (B) Agglomeration of metal particles caused by thermal sintering of the solid surface (C) Covering of the catalytic active sites by a foreign substance (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

‘Lock’ and ‘Key’ model of enzyme action proposed by Fisher implies that (A) The active site is flexible and adjusts to substrate (B) The active site requires removal of PO4 group (C) The active site is complementary in shape to that of the substrate (D) Substrates change conformation prior to active site interaction

Description : Lock' and Key' model of enzyme action proposed by Fisher implies that (A) The active site is flexible and adjusts to substrate (B) The active site requires removal of PO4 group ( ... complementary in shape to that of the substrate (D) Substrates change conformation prior to active site interaction

Last Answer : Answer : C

Match the following. (A) Inhibitor of (i) Ricin catalytic activity (B) Possess peptide (ii) Malonate bonds (C) Cell wall material (iii)Chitin in fungi (D) Secondary (iv) Collagen metabolite Choose the correct option from the following: (A) (B) (C) (D) (a) (ii) (iv) (iii) (i) (b) (iii) (i) (iv) (ii) (c) (iii) (iv) (i) (ii) (d) (ii) (iii) (i) (iv)

Description : Match the following. (A) Inhibitor of (i) Ricin catalytic activity (B) Possess peptide (ii) Malonate bonds (C) Cell wall material (iii)Chitin in fungi (D) Secondary (iv) Collagen metabolite Choose the correct option from the following: (A) ... iv) (ii) (c) (iii) (iv) (i) (ii) (d) (ii) (iii) (i) (iv)

Last Answer : (A) Inhibitor of (i) Ricin catalytic activity

Induction of drug metabolizing enzymes involves: A. A conformational change in the enzyme protein to favour binding of substrate molecules B. Expression of enzyme molecules on the surface of hepatocytes C. Enhanced transport of substrate molecules into hepatocytes D. Increased synthesis of enzyme protein

Description : Induction of drug metabolizing enzymes involves: A. A conformational change in the enzyme protein to favour binding of substrate molecules B. Expression of enzyme molecules on the surface of ... C. Enhanced transport of substrate molecules into hepatocytes D. Increased synthesis of enzyme protein

Last Answer : D. Increased synthesis of enzyme protein

Induction of drug metabolizing enzymes involves: A. A conformational change in the enzyme protein to favour binding of substrate molecules B. Expression of enzyme molecules on the surface of hepatocytes C. Enhanced transport of substrate molecules into hepatocytes D. Increased synthesis of enzyme protein

Description : Induction of drug metabolizing enzymes involves: A. A conformational change in the enzyme protein to favour binding of substrate molecules B. Expression of enzyme molecules on the surface of ... C. Enhanced transport of substrate molecules into hepatocytes D. Increased synthesis of enzyme protein

Last Answer : D. Increased synthesis of enzyme protein

Choose the correct statement about allopurinol: A. It is a purine antimetabolite with antineoplastic activity B. It is a competitive inhibitor of xanthine oxidase C. It is inactive itself, but its metabolite alloxanthine is a competitive inhibitor of xanthine oxidase D. Both allopurinol as well as its metabolite alloxanthine are noncompetitive inhibitors of xanthine oxidase

Description : Choose the correct statement about allopurinol: A. It is a purine antimetabolite with antineoplastic activity B. It is a competitive inhibitor of xanthine oxidase C. It is inactive itself ... D. Both allopurinol as well as its metabolite alloxanthine are noncompetitive inhibitors of xanthine oxidase

Last Answer : B. It is a competitive inhibitor of xanthine oxidase

What happens to an enzyme when a competitive inhibitor binds to it?

Description : What happens to an enzyme when a competitive inhibitor binds to it?

Last Answer : Need answer

A competitive inhibitor of an enzyme (A) Increases Km without affecting Vmax (B) Decreases Km without affecting Vmax (C) Increases Vmax without affecting Km (D) Decreases both Vmax and Km

Description : A competitive inhibitor of an enzyme (A) Increases Km without affecting Vmax (B) Decreases Km without affecting Vmax (C) Increases Vmax without affecting Km (D) Decreases both Vmax and Km

Last Answer : Answer : A

The kinetic effect of purely competitive inhibitor of an enzyme (A) Increases Km without affecting Vmax (B) Decreases Km without affecting Vmax (C) Increases Vmax without affecting Km (D) Decreases Vmax without affecting Km

Description : The kinetic effect of purely competitive inhibitor of an enzyme (A) Increases Km without affecting Vmax (B) Decreases Km without affecting Vmax (C) Increases Vmax without affecting Km (D) Decreases Vmax without affecting Km

Last Answer : Answer : A

The following is a competitive type of enzyme inhibitor: A. Acetazolamide B. Disulfiram C. Physostigmine D. Theophylline

Description : The following is a competitive type of enzyme inhibitor: A. Acetazolamide B. Disulfiram C. Physostigmine D. Theophylline

Last Answer : C. Physostigmine

The following is a competitive type of enzyme inhibitor: A. Acetazolamide B. Disulfiram C. Physostigmine D. Theophylline

Description : The following is a competitive type of enzyme inhibitor: A. Acetazolamide B. Disulfiram C. Physostigmine D. Theophylline

Last Answer : C. Physostigmine

If an enzyme‘s active site becomes deformed, inhibition was likely responsible. a. Metabolic b. Competitive c. Noncompetitive d. Cellular

Description : If an enzyme‘s active site becomes deformed, inhibition was likely responsible. a. Metabolic b. Competitive c. Noncompetitive d. Cellular

Last Answer : c. Noncompetitive

Ribozyme is: (a) enzyme (b) RNA with enzymatic activity (c) Hormone (d) Protein

Description : Ribozyme is: (a) enzyme (b) RNA with enzymatic activity (c) Hormone (d) Protein

Last Answer : Ans. ((b))

An enzyme promotes a chemical reaction by (A) Lowering the energy of activation (B) Causing the release of heat which acts as a primer (C) Increasing molecular motion (D) Changing the free energy difference between substrate and product

Description : An enzyme promotes a chemical reaction by (A) Lowering the energy of activation (B) Causing the release of heat which acts as a primer (C) Increasing molecular motion (D) Changing the free energy difference between substrate and product

Last Answer : Answer : A

Allosteric enzymes regulate the formation of products by (A) Feedback inhibition (B) Non-competitive inhibition (C) Competitive inhibition (D) Repression-derepression

Description : Allosteric enzymes regulate the formation of products by (A) Feedback inhibition (B) Non-competitive inhibition (C) Competitive inhibition (D) Repression-derepression

Last Answer : Answer : A

Allosteric inhibition is also known as (A) Competitive inhibition (B) Non-competitive inhibition (C) Feedback inhibition (D) None of these

Description : Allosteric inhibition is also known as (A) Competitive inhibition (B) Non-competitive inhibition (C) Feedback inhibition (D) None of these

Last Answer : Answer : C

Consider the following statements. (A) Coenzyme or metal ion that is tightly bound to enzyme protein is called prosthetic group. (B) A complete catalytic active enzyme with its bound prosthetic group is called apoenzyme. Select the correct option. (a) (A) is false but (B) is true. (b) Both (A) and (B) are true. (c) (A) is true but (B) is false. (d) Both (A) and (B) are false

Description : Consider the following statements. (A) Coenzyme or metal ion that is tightly bound to enzyme protein is called prosthetic group. (B) A complete catalytic active enzyme with its bound prosthetic group is called apoenzyme. Select the ... ) (A) is true but (B) is false. (d) Both (A) and (B) are false

Last Answer : (d) Both (A) and (B) are false.

In non-competitive enzyme action (A) Vmax is increased (B) Apparent km is increased (C) Apparent km is decreased (D) Concentration of active enzyme molecule is reduced

Description : In non-competitive enzyme action (A) Vmax is increased (B) Apparent km is increased (C) Apparent km is decreased (D) Concentration of active enzyme molecule is reduced

Last Answer : Answer : C

AMP is an allosteric inhibitor of (A) PRPP synthetase (B) Adenylosucciante synthetase (C) Both (A) and (B) (D) None of these

Description : AMP is an allosteric inhibitor of (A) PRPP synthetase (B) Adenylosucciante synthetase (C) Both (A) and (B) (D) None of these

Last Answer : Answer : C

GMP is an allosteric inhibitor of all the following except (A) PRPP synthetase (B) PRPP glutamyl amido synthetase (C) IMP dehydrogenase (D) Adenylosuccinate synthetase

Description : GMP is an allosteric inhibitor of all the following except (A) PRPP synthetase (B) PRPP glutamyl amido synthetase (C) IMP dehydrogenase (D) Adenylosuccinate synthetase

Last Answer : Answer : D

An allosteric inhibitor of IMP dehydrogenase is (A) AMP (B) ADP (C) GMP (D) GDP

Description : An allosteric inhibitor of IMP dehydrogenase is (A) AMP (B) ADP (C) GMP (D) GDP

Last Answer : Answer : C

An allosteric inhibitor of adenylosuccinate synthetase is (A) AMP (B) ADP (C) GMP (D) GDP

Description : An allosteric inhibitor of adenylosuccinate synthetase is (A) AMP (B) ADP (C) GMP (D) GDP

Last Answer : Answer : A

An allosteric inhibitor of PRPP glutamyl amido transferase is (A) AMP (B) ADP (C) GMP (D) All of these

Description : An allosteric inhibitor of PRPP glutamyl amido transferase is (A) AMP (B) ADP (C) GMP (D) All of these

Last Answer : Answer : C

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

An allosteric inhibitor of pyruvate dehydrogenase is (A) Acetyl CoA (B) ATP (C) NADH (D) Pyruvate

Description : An allosteric inhibitor of pyruvate dehydrogenase is (A) Acetyl CoA (B) ATP (C) NADH (D) Pyruvate

Last Answer : Answer : A