Đề 4 – Bài tập, đề thi trắc nghiệm online Hóa sinh enzyme

A A. The maximum velocity of an enzyme-catalyzed reaction. B B. The substrate concentration at which the reaction rate is half of Vmax. C C. The dissociation constant of the enzyme-substrate complex. D D. The turnover number of an enzyme.

A A. The temperature of the enzyme. B B. The concentration of the substrate. C C. The ionization state of amino acid residues in the active site. D D. The overall size of the enzyme molecule.

A A. They increase the activation energy of the reaction. B B. They stabilize the enzyme-substrate complex. C C. They bind to the enzyme more tightly than the substrate, mimicking the transition state. D D. They act as coenzymes in the reaction.

A A. Hydrolysis reactions. B B. Oxidation-reduction reactions. C C. Group transfer reactions. D D. Cleavage of bonds by means other than hydrolysis or oxidation.

A A. Enzymes that catalyze different reactions but use the same substrate. B B. Physically different forms of the same enzyme that catalyze the same reaction. C C. Enzymes that are active only at very high temperatures. D D. Enzymes that require different cofactors for activity.

A A. Enzymes are specific to the type of reaction but not the substrate. B B. Enzyme specificity arises from the unique 3D structure of the active site. C C. Enzyme specificity is only determined by the primary structure of the enzyme. D D. All enzymes exhibit absolute specificity for only one substrate.

A A. Increasing the Km but not Vmax. B B. Decreasing both Km and Vmax. C C. Decreasing Vmax but not Km. D D. Increasing both Km and Vmax.

A A. Binding to the enzyme active site temporarily. B B. Forming a covalent bond with the enzyme, permanently inactivating it. C C. Changing the enzyme's Km but not Vmax. D D. Binding to an allosteric site and changing enzyme conformation reversibly.

A A. Allosteric site. B B. Active site. C C. Binding domain. D D. Prosthetic group.

A A. Non-competitive inhibition. B B. Uncompetitive inhibition. C C. Competitive inhibition. D D. Irreversible inhibition.

A A. The conformational change of the enzyme upon substrate binding. B B. The rigid active site of the enzyme that perfectly fits the substrate. C C. The induced fit between enzyme and substrate. D D. The mechanism of competitive inhibition.

A A. Activation of the first enzyme in the pathway by the end product. B B. Inhibition of the first enzyme in the pathway by the end product. C C. Activation of the last enzyme in the pathway by the initial substrate. D D. Inhibition of the last enzyme in the pathway by the initial substrate.

A A. The enzyme active site is always perfectly complementary to the substrate. B B. Both the enzyme and the substrate undergo conformational changes upon binding. C C. Only the substrate changes shape upon binding to the enzyme. D D. This model is only applicable to allosteric enzymes.

A A. 0°C. B B. 25°C. C C. 37°C. D D. 100°C.

A A. Temperature. B B. pH. C C. Enzyme concentration. D D. Product concentration (in typical in vivo conditions).

A A. Can catalyze a wide range of reactions. B B. Typically catalyze only one specific reaction or a small set of closely related reactions. C C. Work equally well with all types of substrates. D D. Are active in all cellular compartments.

A A. Reactions involving water as a reactant to break bonds. B B. Reactions that remove groups to form double bonds. C C. Reactions that change the stereochemistry of molecules. D D. Reactions that combine two molecules using ATP.

A A. Determine the optimal pH for enzyme activity. B B. Linearize Michaelis-Menten kinetics data for easier determination of Km and Vmax. C C. Separate different isozymes of an enzyme. D D. Measure the temperature stability of an enzyme.

A A. Following Michaelis-Menten kinetics strictly. B B. Having a hyperbolic relationship between reaction rate and substrate concentration. C C. Having multiple active sites. D D. Having sigmoidal kinetics due to cooperativity.

A A. The removal of water to form a double bond. B B. The addition of water to break a bond. C C. The rearrangement of atoms within a molecule. D D. The transfer of phosphate groups.

A A. Zinc ion (Zn2+). B B. Magnesium ion (Mg2+). C C. Nicotinamide adenine dinucleotide (NAD+). D D. Chloride ion (Cl-).

A A. Transferases. B B. Hydrolases. C C. Oxidoreductases. D D. Isomerases.

A A. Only the protein part (apoenzyme). B B. Only the cofactor. C C. The apoenzyme and the cofactor. D D. Multiple subunits of enzyme molecules.

A A. The protein part of an enzyme. B B. A non-protein molecule or ion required for enzyme activity. C C. Another name for the substrate. D D. A product of the enzyme-catalyzed reaction.

A A. To determine the 3D structure of enzymes. B B. To understand the mechanism of enzyme-catalyzed reactions and factors affecting their rates. C C. To identify the cofactors required by enzymes. D D. To classify enzymes into different groups.

A A. Cleavage of bonds with the addition of water. B B. Transfer of functional groups from one molecule to another. C C. Rearrangement of atoms within a molecule. D D. Joining of two molecules together.

A A. Hydrolases. B B. Isomerases. C C. Polymerases. D D. Ligases.

A A. Breakdown of large molecules into smaller ones. B B. Formation of bonds, often coupled with ATP hydrolysis. C C. Transfer of electrons between molecules. D D. Rearrangement of functional groups within a molecule.

A A. Increasing the activation energy of a reaction. B B. Decreasing the activation energy of a reaction. C C. Changing the equilibrium constant of a reaction. D D. Being consumed during the reaction process.

A A. Binds only to the enzyme-substrate complex. B B. Binds to the enzyme at a site other than the active site. C C. Increases the Vmax of the enzyme. D D. Binds to the active site of the enzyme, competing with the substrate.