Enzymology: Master the Fundamentals of Biological Catalysts

Question 1

The Michaelis-Menten equation is used to describe:

Accepted Answer

The relationship between enzyme activity and substrate concentration.

Answer

The mechanism by which enzymes catalyze reactions.

Answer

The effect of inhibitors on enzyme activity.

Answer

The structure of the enzyme-substrate complex.

Question 2

The active site of an enzyme is the region of the enzyme where:

Accepted Answer

Substrate binds

Answer

Cofactors bind

Answer

Hydrolysis reaction occurs

Answer

Enzyme regulation takes place

Question 3

The Michaelis-Menten constant (Km) represents:

Accepted Answer

Substrate concentration at which the enzyme is half-saturated

Answer

Maximum velocity of the enzyme-catalyzed reaction

Answer

Equilibrium constant for enzyme-substrate complex formation

Answer

Rate constant for the enzyme-catalyzed reaction

Question 4

Which of the following is an example of an isoenzyme?

Accepted Answer

Lactate dehydrogenase

Answer

Hemoglobin

Answer

Insulin

Answer

Myoglobin

Question 5

Where is the active site of an enzyme located?

Accepted Answer

The region where the substrate binds and is converted into the product

Answer

The region where the enzyme binds to cofactors

Answer

The region where the enzyme is synthesized

Answer

The region where the enzyme interacts with inhibitors

Question 6

What does the Michaelis-Menten constant (Km) represent?

Accepted Answer

The substrate concentration at which the reaction rate is half-maximal

Answer

The enzyme concentration at which the reaction rate is half-maximal

Answer

The rate constant for the enzyme-catalyzed reaction

Answer

The equilibrium constant for the enzyme-catalyzed reaction

Question 7

Which of the following describes competitive inhibition?

Accepted Answer

The inhibitor binds to the active site of the enzyme.

Answer

The inhibitor binds to the enzyme-substrate complex.

Answer

The inhibitor binds to a site other than the active site and changes the enzyme's conformation.

Answer

The inhibitor does not bind to the enzyme or substrate, but affects the reaction rate.

Question 8

What is the primary role of cofactors in enzyme catalysis?

Accepted Answer

They participate directly in the catalytic reaction.

Answer

They help stabilize the enzyme's structure.

Answer

They provide the energy required for the reaction to occur.

Answer

They remove the products from the reaction.

Question 9

What is the difference between a holoenzyme and an apoenzyme?

Accepted Answer

A holoenzyme is an enzyme with its cofactor bound, while an apoenzyme lacks its cofactor.

Answer

An apoenzyme is an enzyme with its cofactor bound, while a holoenzyme lacks its cofactor.

Answer

Holoenzymes and apoenzymes are the same thing.

Answer

There is no such thing as a holoenzyme or an apoenzyme.

Question 10

How do enzymes catalyze reactions?

Accepted Answer

By all of the above mechanisms.

Answer

By lowering the activation energy of the reaction.

Answer

By providing a template for the reaction to occur.

Answer

By orienting the substrate molecules correctly.

Question 11

How does the induced fit model explain enzyme specificity?

Accepted Answer

The enzyme changes shape to accommodate the substrate, increasing its specificity.

Answer

The substrate changes shape to accommodate the enzyme, increasing its specificity.

Answer

The induced fit model does not play a role in enzyme specificity.

Answer

Enzyme specificity is determined solely by the amino acid sequence of the enzyme.

Question 12

How does temperature affect enzyme activity?

Accepted Answer

Enhances activity up to an optimal temperature

Answer

Diminishes activity as temperature rises

Answer

Has no effect on enzyme activity

Answer

Continuously increases enzyme activity

Question 13

What is the primary function of coenzymes in enzyme reactions?

Accepted Answer

Donating or accepting electrons/protons

Answer

Providing additional substrate binding sites

Answer

Increasing reaction rates

Answer

Stabilizing the reaction's transition state

Question 14

Define the Michaelis constant (Km).

Accepted Answer

Substrate concentration at which the enzyme is half-saturated

Answer

Maximum velocity of the enzyme-catalyzed reaction

Answer

Equilibrium constant of the enzyme-catalyzed reaction

Answer

Rate constant of the enzyme-catalyzed reaction

Question 15

Which attribute of enzymes is **incorrect**?

Accepted Answer

Enzymes are consumed as part of the reaction.

Answer

Enzymes decrease the activation energy of reactions.

Answer

Enzymes are highly selective for specific substrates.

Answer

Enzymes are mostly composed of proteins.

Question 16

Define the active site of an enzyme.

Accepted Answer

A specific region of an enzyme that combines with the substrate.

Answer

The complete external surface of the enzyme.

Answer

An area of the enzyme that is unaffected by changes in pH.

Question 17

What does the Michaelis constant (Km) represent in enzyme kinetics?

Accepted Answer

The substrate concentration when the enzyme is half-saturated.

Answer

The affinity between an enzyme and its substrate.

Answer

The highest rate of an enzyme-catalyzed reaction.

Question 18

Allosteric enzyme regulation involves:

Accepted Answer

Regulatory molecules binding to specific sites on the enzyme.

Answer

Irreversible chemical modifications of the enzyme.

Answer

Changes in enzyme structure without ligand binding.

Question 19

What is the common catalytic mechanism employed by most enzymes?

Accepted Answer

Formation of an enzyme-substrate complex.

Answer

Oxidation of the substrate.

Answer

Hydrolysis of the substrate.

Answer

Direct transfer of electrons.

Question 20

Protein folding into functional conformations is aided by:

Accepted Answer

Chaperones.

Answer

Nucleic acids.

Answer

Enzymes.

Question 21

The active site of an enzyme is:

Accepted Answer

A specific region of the enzyme that binds to the substrate.

Answer

The entire surface of the enzyme.

Answer

A random area of the enzyme that varies depending on the substrate.

Question 22

The Michaelis constant (Km) is a measure of:

Accepted Answer

The substrate concentration at which the enzyme is half-saturated.

Answer

The specificity of the enzyme for its substrate.

Answer

The maximum rate of enzyme activity.

Question 23

Which of the following is a mechanism of enzyme catalysis?

Accepted Answer

Lowering the activation energy of the reaction.

Answer

Increasing the number of reactants.

Answer

Providing a template for the reaction.

Answer

Changing the equilibrium of the reaction.

Question 24

Which of the following is a cofactor for many enzymes?

Accepted Answer

NAD+

Answer

Water

Answer

Glucose