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

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
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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 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

Description : 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

Last Answer : Ans. ((d))

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

Feedback inhibition of enzyme is influenced by (A) Enzyme (B) External factors (C) End product (D) Substrate

Description : Feedback inhibition of enzyme is influenced by (A) Enzyme (B) External factors (C) End product (D) Substrate

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

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.

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

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

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

Feedback inhibition of enzyme action is affected by (A) Enzyme (B) Substrate (C) End products (D) None of these

Description : Feedback inhibition of enzyme action is affected by (A) Enzyme (B) Substrate (C) End products (D) None of these

Last Answer : Answer : C

Which factor is responsible for inhibition of enzymatic process during feedback? (a) Substrate (b) Enzymes (c) End product (d) Temperature

Description : Which factor is responsible for inhibition of enzymatic process during feedback? (a) Substrate (b) Enzymes (c) End product (d) Temperature

Last Answer : (c) End product

The organophosphates produce irreversible inhibition of cholinesterase because: A. They bind to an allosteric site of the enzyme resulting in unfavourable conformation of esteratic site to bind acetylcholine B. Regeneration time of the phosphorylated enzyme is longer than the turnover time of the enzyme molecules C. Phosphorylation results in rapid degradation of enzyme molecules D. They are neither metabolized nor excreted from the body

Description : The organophosphates produce irreversible inhibition of cholinesterase because: A. They bind to an allosteric site of the enzyme resulting in unfavourable conformation of esteratic site to bind ... degradation of enzyme molecules D. They are neither metabolized nor excreted from the body

Last Answer : B. Regeneration time of the phosphorylated enzyme is longer than the turnover time of the enzyme molecules

The organophosphates produce irreversible inhibition of cholinesterase because: A. They bind to an allosteric site of the enzyme resulting in unfavourable conformation of esteratic site to bind acetylcholine B. Regeneration time of the phosphorylated enzyme is longer than the turnover time of the enzyme molecules C. Phosphorylation results in rapid degradation of enzyme molecules D. They are neither metabolized nor excreted from the body

Description : The organophosphates produce irreversible inhibition of cholinesterase because: A. They bind to an allosteric site of the enzyme resulting in unfavourable conformation of esteratic site to bind ... degradation of enzyme molecules D. They are neither metabolized nor excreted from the body

Last Answer : B. Regeneration time of the phosphorylated enzyme is longer than the turnover time of the enzyme molecules

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 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

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

An example of feedback inhibition is (A) Allosteric inhibition of hexokinase by glucose6-phosphate (B) Cyanide action on cytochrome (C) Sulpha drug on folic acid synthesizer bacteria (D) Reaction between succinic dehydrogenase and succinic acid

Description : An example of feedback inhibition is (A) Allosteric inhibition of hexokinase by glucose6-phosphate (B) Cyanide action on cytochrome (C) Sulpha drug on folic acid synthesizer bacteria (D) Reaction between succinic dehydrogenase and succinic acid

Last Answer : Answer : A

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

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

An example of enzyme inhibition: (A) Reversible inhibition (B) Irreversible inhibition (C) Allosteric inhibition (D) All of these ENZYMES 151

Description : An example of enzyme inhibition: (A) Reversible inhibition (B) Irreversible inhibition (C) Allosteric inhibition (D) All of these ENZYMES 151

Last Answer : Answer : D

Give examples for allosteric inhibition.

Description :  Give examples for allosteric inhibition.

Last Answer : ALA synthase, aspartyl trans-carbamoylase, HMG CoA reductase

What are the salient features of allosteric inhibition?

Description : What are the salient features of allosteric inhibition?

Last Answer : (1) The inhibitor is not a substrate analogue. (2) It is partially reversible when excess substrate is added. (3) Km is usually increased. (4) Vmax is reduced. (5) Most allosteric enzymes possess quaternary structure. They are made up of subunits.

What is allosteric inhibition?

Description : What is allosteric inhibition?

Last Answer : Allosteric enzyme has one catalytic site where the substrate binds and another separate allosteric site where the modifier binds.

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

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

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

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

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

‘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

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

Enzymes combine with a ___________at the___________ site to lower the activation energy. a. Substrate; Active b. Product; Noncompetitive c. Product; Active d. Coenzyme; Active

Description : Enzymes combine with a ___________at the___________ site to lower the activation energy. a. Substrate; Active b. Product; Noncompetitive c. Product; Active d. Coenzyme; Active

Last Answer : a. Substrate; Active

Difference between competitive and allosteric inhibition -Biology

Description : Difference between competitive and allosteric inhibition -Biology

Last Answer : answer:

The sulfa drugs work by _______ with PABA in making folic acid. a. Positive Feedback b. Negative Feedback c. Competitive Inhibition d. Allosteric Inhibition

Description : The sulfa drugs work by _______ with PABA in making folic acid. a. Positive Feedback b. Negative Feedback c. Competitive Inhibition d. Allosteric Inhibition

Last Answer : c. Competitive Inhibition

Negative regulation of protein synthesis is accomplished by A- allosteric inhibition B- the binding of RNA polymerase to the promoter C- the binding of a repressor to the DNA D- the binding of a repressor to the RNA polymerase

Description : Negative regulation of protein synthesis is accomplished by A- allosteric inhibition B- the binding of RNA polymerase to the promoter C- the binding of a repressor to the DNA D- the binding of a repressor to the RNA polymerase

Last Answer : the binding of a repressor to the DNA

Which of the following is the correct matchin of the site of action on the given substrate, the enzyme acting state upon it and the end product

Description : Which of the following is the correct matchin of the site of action on the given substrate, the enzyme acting state upon it and the end product

Last Answer : Which of the following is the correct matchin of the site of action on the given substrate, the ... alpha`-amylase `rarr` Disac- charide (Maltose)

Which one of the following is the correct matching of the site of action on the given substrate, the enzyme acting upon it and the end product? (a) Small intestine : Proteins Pepsin  →  Amino acids (b) Stomach : Fats Lipase  →  Micelles (c) Duodenum : Triglycerides Trypsin  →  Monoglycerides (d) Small intestine : Starch α-Amylase  →  Disaccharide (maltose)

Description : Which one of the following is the correct matching of the site of action on the given substrate, the enzyme acting upon it and the end product? (a) Small intestine : Proteins Pepsin  →  ... Trypsin  →  Monoglycerides (d) Small intestine : Starch α-Amylase  →  Disaccharide (maltose)

Last Answer : (d) Small intestine : Starch α-Amylase  →  Disaccharide

If all the enzymes, intermediates and cofactors of the citric acid cycle as well as an excess of the starting substrate acetylCoA are present and functional in an organelle free solution at the appropriate pH, which of the following factors of the citric acid cycle would prove to be rate limiting? (A) Molecular oxygen (B) Half life of enzyme (C) Turnover of intermediates (D) Reduction of cofactors

Description : If all the enzymes, intermediates and cofactors of the citric acid cycle as well as an excess of the starting substrate acetylCoA are present and functional in an organelle free solution at the appropriate ... oxygen (B) Half life of enzyme (C) Turnover of intermediates (D) Reduction of cofactors

Last Answer : Answer : D

.Gene regulation governing lactose operon of E.coli that involves the lac I gene product is (a) negative and repressible because repressor protein prevents transcription (b) feedback inhibition because excess of β-galactosidase can switch off transcription (c) positive and inducible because it can be induced by lactose (d) negative and inducible because repressor protein prevents transcription.

Description : .Gene regulation governing lactose operon of E.coli that involves the lac I gene product is (a) negative and repressible because repressor protein prevents transcription (b) feedback inhibition ... be induced by lactose (d) negative and inducible because repressor protein prevents transcription.

Last Answer : (d) negative and inducible because repressor protein prevents transcription.

Gene regulation governing lactose operon of E.coli that involves the lac I gene product is (a) negative and repressible because repressor protein prevents transcription (b) feedback inhibition because excess of β-galactosidase can switch off transcription (c) positive and inducible because it can be induced by lactose (d) negative and inducible because repressor protein prevents transcription.

Description : Gene regulation governing lactose operon of E.coli that involves the lac I gene product is (a) negative and repressible because repressor protein prevents transcription (b) feedback inhibition ... be induced by lactose (d) negative and inducible because repressor protein prevents transcription.

Last Answer : (d) negative and inducible because repressor protein prevents transcription.

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 hypothesis to explain enzyme– substrate complex formation: (A) Lock and key model (B) Induced fit theory (C) Proenzyme theory (D) Both (A) and (B)

Description : The hypothesis to explain enzyme– substrate complex formation: (A) Lock and key model (B) Induced fit theory (C) Proenzyme theory (D) Both (A) and (B)

Last Answer : Answer : C

Feedback term refers to (A) Effect of substrate on rate of enzymatic reaction (B) Effect of end product on rate reaction (C) Effect of enzyme concentration on rate of reaction (D) Effect of external compound on rate of reaction

Description : Feedback term refers to (A) Effect of substrate on rate of enzymatic reaction (B) Effect of end product on rate reaction (C) Effect of enzyme concentration on rate of reaction (D) Effect of external compound on rate of reaction

Last Answer : Answer : B

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

In enzyme kinetics Vmax reflects (A) The amount of an active enzyme (B) Substrate concentration (C) Half the substrate concentration (D) Enzyme substrate complex

Description : In enzyme kinetics Vmax reflects (A) The amount of an active enzyme (B) Substrate concentration (C) Half the substrate concentration (D) Enzyme substrate complex

Last Answer : Answer : A

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

The Michaehis-Menten hypothesis: (A) Postulates the formation of an enzyme substrate complex (B) Enables us to calculate the isoelectric point of an enzyme (C) States that the rate of a chemical reaction may be independent of substrate concentration (D) States that the reaction rate is proportional to substrate concentration

Description : The Michaehis-Menten hypothesis: (A) Postulates the formation of an enzyme substrate complex (B) Enables us to calculate the isoelectric point of an enzyme (C) States that the ... independent of substrate concentration (D) States that the reaction rate is proportional to substrate concentration

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))

Which one of the following is the correct mathcing of the site of action on the given substrate, the enzyme acting upon it and the end producrt?

Description : Which one of the following is the correct mathcing of the site of action on the given substrate, the enzyme acting upon it and the end producrt?

Last Answer : Which one of the following is the correct mathcing of the site of action on the given substrate, ... ( prop "Amylas")(rarr)` Disaccharie (Maltose)