Most Important Enzymes Quiz Test Online

Enzymes Quiz Test Online

Enzymes Test. 1

1 / 20

1) What is formed immediately after the substrate binds to the active site of an enzyme?

Free enzyme and product

Enzyme-substrate complex

Denatured enzyme

Enzyme-product complex

The first step in an enzyme-catalyzed reaction is the reversible binding of the substrate(s) to the active site, leading to the formation of the enzyme-substrate (ES) complex.

2 / 20

2) Enzymes are highly sensitive to changes in environmental conditions, particularly:

Substrate concentration and product concentration.

Humidity and gravitational force.

Temperature and pH.

Light intensity and atmospheric pressure.

Enzymes are proteins, and their intricate three-dimensional structures, including the active site, are highly sensitive to changes in temperature and pH. Deviations from optimal conditions can lead to denaturation and loss of activity.

3 / 20

3) Most enzymes are categorized as which type of macromolecule?

Proteins

Lipids

Nucleic acids

Carbohydrates

The vast majority of enzymes are globular proteins. Their specific three-dimensional structures are crucial for their catalytic activity. Ribozymes (RNA enzymes) are a notable exception.

4 / 20

4) The energy required to initiate a biochemical reaction, even with the presence of an enzyme, is known as:

Free energy

Kinetic energy

Potential energy

Activation energy

Activation energy is the minimum energy that reactant molecules must possess to undergo a chemical reaction. Enzymes lower this energy barrier, thus accelerating the reaction rate without changing the overall energy difference between reactants and products.

5 / 20

5) The specific region on an enzyme where the substrate binds and catalysis occurs is known as the:

Regulatory site

Active site

Inhibitor site

Allosteric site

The active site is a unique three-dimensional cleft or pocket on the enzyme molecule where the substrate specifically binds. This binding facilitates the chemical transformation of the substrate into product.

6 / 20

6) Which of the following statements about enzyme activity is INCORRECT?

Enzymes can catalyze reactions both inside and outside living cells.

Enzymes are highly specific for their substrates.

Enzymes change the equilibrium constant of a reaction.

Some enzymes require non-protein components for their activity.

Enzymes accelerate the rate at which equilibrium is reached, but they do not change the position of the equilibrium itself. The equilibrium constant remains unchanged whether an enzyme is present or not. Enzymes can work in vivo and in vitro, are highly specific, and often require cofactors.

7 / 20

7) The tertiary or quaternary structures of enzymes are crucial because they:

Allow for their easy transportation across membranes.

Determine their solubility in water.

Are responsible for their color.

Form the specific active site necessary for catalysis.

The specific three-dimensional folding of the polypeptide chain(s) (tertiary and quaternary structures) creates the unique shape of the active site. This precise geometry is essential for the specific binding of the substrate and the subsequent catalytic event.

8 / 20

8) Which statement best describes the quantity of enzymes required for a biochemical reaction?

Large quantities are needed as they are consumed in the reaction.

They are only needed in vitro, not in vivo.

The quantity needed is equal to the quantity of substrate.

They are required in very small quantities and are reusable.

Enzymes are biological catalysts, and like all catalysts, they are not consumed during the reaction. They are regenerated after each catalytic cycle, meaning only very small quantities are sufficient to convert large amounts of substrate into product.

9 / 20

9) Within the active site, the amino acids responsible for chemically transforming the substrate are part of the:

Binding site

Regulatory site

Allosteric site

Catalytic site

The active site can often be divided into two main parts: the binding site, which holds the substrate in place, and the catalytic site, which contains the amino acid residues directly involved in the chemical conversion of the substrate into product.

10 / 20

10) Which statement correctly describes the effect of an enzyme on a biochemical reaction?

It increases the equilibrium constant.

It increases the rate at which the reaction reaches equilibrium.

It makes an unfavorable reaction favorable.

It changes the overall Gibb's free energy (ΔG) of the reaction.

Enzymes accelerate the rate of reaction by lowering the activation energy, thereby allowing the system to reach chemical equilibrium more quickly. However, they do not alter the position of the equilibrium or the overall free energy change of the reaction (ΔG).

11 / 20

11) The active site of an enzyme is best described as a:

Flat surface where any molecule can bind.

Linear chain of amino acids.

Three-dimensional, charge-bearing cavity.

Storage region for excess substrate molecules.

The active site is a precisely shaped, three-dimensional region on the enzyme molecule. Its specific spatial arrangement and charge distribution allow it to bind selectively with its complementary substrate, forming the enzyme-substrate complex.

12 / 20

12) An enzyme's ability to catalyze a specific reaction efficiently is largely due to its:

Unique active site structure.

Presence of disulfide bonds only.

Large molecular weight.

Globular shape.

The high specificity and catalytic efficiency of an enzyme are primarily attributed to the unique three-dimensional conformation of its active site. This site is precisely shaped to bind only specific substrate molecules, enabling specific chemical transformations.

13 / 20

13) Enzymes primarily function by:

Providing an alternative reaction pathway with lower activation energy.

Decreasing the stability of the products.

Increasing the temperature of the reaction system.

Increasing the activation energy of the reaction.

The fundamental mechanism of enzyme action involves lowering the activation energy, which is the minimum energy required for a chemical reaction to occur. By doing so, enzymes increase the rate of reaction without being used up in the process.

14 / 20

14) According to the Lock and Key Model of enzyme action:

The enzyme's active site has a rigid, pre-formed shape complementary to the substrate.

Substrates induce a conformational change in the enzyme's active site.

Multiple enzymes can bind to a single substrate.

The active site is flexible and changes shape upon substrate binding.

Proposed by Emil Fischer, the Lock and Key Model suggests that the active site of an enzyme is rigid and has a fixed shape that perfectly matches the shape of its specific substrate, much like a key fits into a lock.

15 / 20

15) Ribozymes are a unique class of enzymes primarily composed of:

Lipids

RNA

Carbohydrates

DNA

While most enzymes are proteins, ribozymes are catalytic RNA molecules. A well-known example is the peptidyl transferase activity of ribosomal RNA, which catalyzes peptide bond formation during protein synthesis.

16 / 20

16) Which of the following is true regarding enzyme action and activation energy?

Enzymes convert all the activation energy into heat.

Enzymes do not affect the activation energy.

Enzymes provide an alternative reaction pathway with a lower activation energy.

Enzymes increase the energy required for a reaction to start.

Enzymes catalyze reactions by lowering the activation energy, which is the energy barrier that must be overcome for reactants to be converted into products. They achieve this by stabilizing the transition state, making the reaction more favorable.

17 / 20

17) Enzymes accelerate biochemical reactions by:

Lowering the activation energy.

Increasing the concentration of products.

Increasing the kinetic energy of reactants.

Shifting the equilibrium of the reaction.

Enzymes function by providing an alternative reaction pathway with a lower activation energy. This allows a greater proportion of reactant molecules to possess sufficient energy to undergo the reaction, thereby increasing the reaction rate without affecting the overall equilibrium or the final product concentration.

18 / 20

18) Cofactors are often required for enzyme activity. They are typically:

Products of the enzymatic reaction.

Non-protein components that aid in catalysis.

Large protein molecules that assist in denaturation.

Inhibitors that block the active site.

Cofactors are non-protein chemical components (like inorganic ions or coenzymes) that are essential for the activity of many enzymes. They may participate directly in the catalytic mechanism or help in substrate binding.

19 / 20

19) The Induced Fit Model suggests that:

The enzyme's active site is permanently rigid.

The substrate's shape changes to fit the enzyme.

The active site undergoes a conformational change upon substrate binding.

Enzymes are non-regulatory and have absolute specificity.

Developed by Koshland, the Induced Fit Model proposes that the active site is not rigid but flexible. When the substrate binds, it induces a slight conformational change in the enzyme, molding the active site into a more precise fit for catalysis.

20 / 20

20) Which of the following is a primary distinguishing characteristic of enzymes?

They are highly specific in their action.

They increase the activation energy of a reaction.

They are consumed during the reaction.

They are always simple proteins.

Enzymes are biological catalysts known for their high specificity, meaning each enzyme typically acts on a particular substrate or a group of structurally similar substrates. They are not consumed, they lower activation energy, and while most are proteins, some are RNA molecules (ribozymes).

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Enzymes Test. 2

1 / 20

1) If the graph of reaction rate versus temperature for a human enzyme shows a sharp decrease after the optimum, this is primarily due to:

Formation of precipitate.

Reversible inactivation.

Permanent denaturation of the enzyme.

Increased substrate inhibition.

The sharp decrease is due to irreversible denaturation of the enzyme beyond its optimum temperature.

2 / 20

2) Extreme changes in pH can lead to irreversible loss of enzyme activity primarily by:

Increasing the enzyme's affinity for its substrate.

Reducing the kinetic energy of the enzyme molecules.

Disrupting the ionic and hydrogen bonds that maintain the enzyme's tertiary structure.

Altering the enzyme's primary amino acid sequence.

Extreme pH values disrupt key bonds that maintain the enzyme's structure, causing denaturation.

3 / 20

3) Which of the following best describes the role of enzymes in metabolic pathways?

They direct the pathway towards the formation of specific products.

They primarily store genetic information for the pathway.

They provide the energy needed for the reactions.

They act as structural components of the pathway.

Enzymes are highly specific and catalyze particular reactions in a sequential manner within metabolic pathways. This specificity ensures that the correct products are formed efficiently, directing the flow of metabolites through the pathway.

4 / 20

4) In a reaction with a fixed amount of enzyme, as substrate concentration increases, the reaction rate will initially increase but eventually plateau. This plateau indicates:

All active sites of the enzyme are saturated with substrate.

The enzyme is denatured.

The reaction has reached its equilibrium.

The temperature is too high.

At high substrate concentrations, all active sites are occupied. The enzyme is working at its maximum rate (Vmax).

5 / 20

5) Which of the following is NOT a step in the general mechanism of enzyme action?

Conversion of substrate to product.

Formation of an enzyme-substrate complex.

Permanent alteration of the enzyme's active site.

Release of enzyme from the product.

Enzymes are biological catalysts that are reused repeatedly. Their active site regains its original conformation after the reaction, ready to bind to another substrate molecule. A permanent alteration would imply the enzyme is consumed or denatured.

6 / 20

6) At what approximate temperature do most human enzymes exhibit their maximum activity?

0°C

37°C

88.6°C

25°C

Most human enzymes are optimally active at temperatures close to normal human body temperature, which is approximately 37-38°C. Temperatures significantly above or below this range can reduce or abolish their activity.

7 / 20

7) Pepsin, an enzyme found in the stomach, has an optimum pH of approximately 2.0. This indicates that:

Its active site is adapted to highly acidic environments.

It only functions in the presence of high salt concentrations.

It is inactivated in acidic conditions.

It functions best in a neutral environment.

Pepsin is adapted to the highly acidic conditions of the stomach, with optimal activity at pH ~2.

8 / 20

8) A holoenzyme is formed when an apoenzyme combines with a:

Cofactor

Inhibitor

Substrate

Product

An apoenzyme is the protein component of an enzyme that is inactive on its own. It becomes active, forming a holoenzyme, when it binds to its specific non-protein cofactor (which can be an inorganic ion or a coenzyme).

9 / 20

9) The term "transition state" in an enzyme-catalyzed reaction refers to:

The initial state of the reactants.

The final state of the products.

The state where the enzyme is denatured.

A high-energy, unstable intermediate formed during the reaction.

The transition state is a transient, high-energy, unstable intermediate structure formed during the conversion of reactants to products. Enzymes stabilize this transition state, thereby lowering the activation energy required to reach it.

10 / 20

10) Which model of enzyme action is better suited for explaining the action of regulatory enzymes that can bind to more than one related substrate?

Induced Fit Model

Lock and Key Model

Competitive Inhibition Model

Allosteric Model

The Induced Fit Model, with its flexible active site, can better explain the broader specificity of some enzymes that can act on a range of structurally similar substrates, as well as the regulatory mechanisms where substrate binding induces conformational changes.

11 / 20

11) What happens to an enzyme's activity when the temperature rises significantly above its optimum?

The enzyme's tertiary structure is maintained.

The enzyme becomes more efficient.

Denaturation occurs, leading to a loss of catalytic activity.

The enzyme forms stronger bonds with the substrate.

High temperatures disrupt the weak bonds that maintain an enzyme's precise three-dimensional structure. This irreversible change in shape, known as denaturation, destroys the active site and abolishes catalytic activity.

12 / 20

12) If an enzyme has an optimum pH of 2.0, it is likely to be found in which part of the human body?

Blood

Muscle cells

Stomach

Small intestine

An enzyme with an optimum pH of 2.0, such as pepsin, is adapted to function in highly acidic environments. The human stomach contains strong hydrochloric acid, providing the necessary acidic conditions for such enzymes.

13 / 20

13) When an enzyme catalyzes a reaction, it achieves this by:

Providing a microenvironment that facilitates bond breaking and formation.

Consuming the reactants to form an intermediate.

Directly increasing the temperature of the reactants.

Forcing reactants to collide more frequently.

The active site of an enzyme creates a unique microenvironment (e.g., localized pH, charge distribution, desolvation) that precisely positions substrates and stresses specific bonds, thereby facilitating their conversion to products.

14 / 20

14) A characteristic common to both the Lock and Key and Induced Fit models of enzyme action is:

The enzyme undergoes denaturation during catalysis.

Substrate binding occurs at a specific active site.

The active site remains rigid throughout the reaction.

The enzyme is consumed in the reaction.

Both models agree that the substrate binds to a specific region on the enzyme called the active site. The main difference lies in whether this active site is rigid (Lock and Key) or undergoes conformational changes (Induced Fit) upon substrate binding.

15 / 20

15) When an enzyme is exposed to temperatures significantly below its optimum (e.g., near freezing), its activity usually:

Becomes permanently denatured.

Shifts its optimum pH.

Is temporarily inactivated but can regain activity upon warming.

Increases rapidly.

Low temperatures reduce kinetic energy, slowing molecular motion and enzyme activity. However, enzymes generally retain their structure and regain activity when the temperature returns to optimal.

16 / 20

16) Which factor's effect on enzyme activity is often depicted by a bell-shaped curve?

Enzyme concentration

Product concentration

Substrate concentration

Enzyme activity vs. pH often shows a bell-shaped curve, with peak activity at the optimum pH and reduced activity on either side.

17 / 20

17) The maximum velocity (Vmax) of an enzyme-catalyzed reaction occurs when:

The substrate concentration is negligible.

The enzyme is saturated with substrate.

The enzyme concentration is very low.

The pH is extremely acidic or basic.

Vmax is reached when all enzyme molecules are bound to substrate and catalyzing at maximum efficiency.

18 / 20

18) Increasing the temperature of an enzyme-catalyzed reaction typically doubles the reaction rate for every 10°C rise, up to a certain point. This is due to:

Decrease in activation energy.

Formation of stronger enzyme-substrate complexes.

Enzyme denaturation.

Increased kinetic energy and collision frequency between enzyme and substrate.

Within the physiological range, an increase in temperature boosts the kinetic energy of both enzyme and substrate molecules. This leads to more frequent and energetic collisions, thus increasing the probability of enzyme-substrate complex formation and subsequent product formation.

19 / 20

19) The pH at which an enzyme exhibits its maximum activity is called its:

Neutral point

Optimum pH

Isoelectric point

Saturation pH

Each enzyme has a specific pH range at which it functions most efficiently, and the point of peak activity is its optimum pH.

20 / 20

20) How does increasing enzyme concentration affect the rate of an enzyme-catalyzed reaction, assuming substrate is not limiting?

It directly increases the reaction rate.

It decreases the reaction rate.

It decreases the activation energy further.

It has no effect on the reaction rate.

With excess substrate, more enzymes mean more active sites and a directly proportional increase in reaction rate.

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Enzymes Test. 3

1 / 20

1) An enzyme's activity is significantly reduced at a non-optimal pH due to:

A change in the enzyme's primary structure.

Disruption of the enzyme's peptide bonds.

Alterations in the ionization state of amino acid residues.

Increased covalent bonding within the active site.

Non-optimal pH affects ionizable side chains in the enzyme, particularly in the active site, reducing substrate binding and catalysis.

2 / 20

2) Which pair of factors primarily influences the enzyme's three-dimensional structure and, consequently, its active site?

Temperature and pH.

Enzyme concentration and cofactor concentration.

Light intensity and atmospheric pressure.

Substrate concentration and product concentration.

Temperature and pH impact the hydrogen, ionic, and hydrophobic bonds maintaining enzyme structure and active site integrity.

3 / 20

3) If a graph shows enzyme activity sharply declining below its optimum pH, it suggests that:

The enzyme is forming aggregates.

The enzyme is becoming more stable.

The enzyme is becoming saturated.

The active site is gaining more positive charges.

Below optimum pH, increased protonation alters active site charge, impairing substrate interaction and catalysis.

4 / 20

4) The effect of pH on enzyme activity is primarily related to its influence on the:

Overall concentration of water in the reaction.

Molecular weight of the enzyme.

Covalent bonds within the enzyme.

Ionization state of amino acid residues in the active site.

pH affects the ionization of key amino acids, especially at the active site, altering the enzyme's structure and function.

5 / 20

5) If an enzyme functions optimally at a pH of 8.0, it is likely to be active in:

The small intestine

The stomach

The vacuole

The lysosome

Enzymes like trypsin, with optimal activity around pH 8.0, function best in the alkaline environment of the small intestine.

6 / 20

6) The initial rate of an enzyme-catalyzed reaction is often measured because:

Product inhibition becomes significant later.

The temperature is constant only at the beginning.

Substrate concentration is highest at the start.

The enzyme is most stable at the beginning.

At the start, substrate concentration is highest, and product inhibition is negligible, so the initial rate reflects true enzyme activity.

7 / 20

7) Which characteristic distinguishes a competitive inhibitor from a non-competitive inhibitor?

Competitive inhibitors bind irreversibly.

Competitive inhibitors bind to an allosteric site.

Competitive inhibitors are structurally dissimilar to the substrate.

Competitive inhibition can often be overcome by increasing substrate concentration.

Competitive inhibition can be overcome by increasing substrate concentration, allowing the substrate to outcompete the inhibitor.

8 / 20

8) In competitive inhibition, the inhibitor typically binds to the:

Allosteric site

Catalytic site

Product binding site

Active site

Competitive inhibitors compete with the substrate by binding to the enzyme's active site, preventing substrate binding.

9 / 20

9) What happens to enzyme activity when the pH is slightly altered from the optimum, but not to an extreme level?

The enzyme's activity is temporarily reduced due to ionization changes.

The enzyme becomes more active.

The enzyme irreversibly denatures.

The enzyme's primary structure changes.

Minor pH changes may affect ionization of active site residues, temporarily reducing activity, but it's usually reversible.

10 / 20

10) Which statement about the effect of substrate concentration on enzyme activity is correct?

Substrate concentration primarily affects the enzyme's optimal temperature.

At very high substrate concentrations, the enzyme activity decreases rapidly.

Increasing substrate concentration always increases the reaction rate linearly.

The reaction rate reaches Vmax when the enzyme becomes saturated with substrate.

Reaction rate increases with substrate concentration until saturation, at which point Vmax is reached.

11 / 20

11) An enzyme from a psychrophilic organism would likely have an optimum temperature:

Much higher than human enzymes.

That is highly variable.

Similar to human enzymes.

Close to 0°C.

Psychrophilic enzymes are adapted for cold environments and function optimally around 0°C.

12 / 20

12) If the rate of an enzymatic reaction is plotted against enzyme concentration, assuming unlimited substrate, the graph would show a:

Bell-shaped curve.

Linear increase.

Decrease followed by a plateau.

Hyperbolic curve.

With unlimited substrate, more enzyme means more active sites and a linear increase in reaction rate.

13 / 20

13) Non-competitive inhibitors primarily affect enzyme activity by binding to the:

Product.

Allosteric site.

Active site.

Substrate itself.

Non-competitive inhibitors bind to an allosteric site, inducing conformational changes that reduce catalytic efficiency.

14 / 20

14) Consider an enzyme from thermophilic bacteria. Compared to a human enzyme, its optimum temperature would likely be:

Significantly higher.

The same.

Dependent on the substrate.

Significantly lower.

Thermophilic enzymes are adapted to high temperatures, often 70°C or higher, unlike human enzymes (~37°C).

15 / 20

15) Why does the rate of an enzyme-catalyzed reaction decrease at very high substrate concentrations in some?

The active sites are all saturated.

Excess substrate might bind to an allosteric site and inhibit the enzyme.

The product starts inhibiting the enzyme.

The enzyme becomes denatured.

In substrate inhibition, excess substrate may bind to non-catalytic sites, distorting the enzyme and reducing activity.

16 / 20

16) The term "Q10 value" in relation to enzyme activity refers to the factor by which the rate of reaction increases for every:

5°C increase in temperature.

10°C increase in temperature.

1°C increase in temperature.

1 pH unit change.

Q10 is the factor by which reaction rate increases with a 10°C rise in temperature, typically doubling within limits.

17 / 20

17) The effect of enzyme concentration on reaction rate can be understood as:

Enzyme concentration affects the activation energy.

More enzyme molecules.

Each enzyme molecule can only catalyze one reaction.

It is only relevant when substrate is limiting.

More enzymes mean more active sites are available to bind and convert substrate, increasing reaction rate.

18 / 20

18) Which graph represents the effect of enzyme concentration on the rate of reaction when substrate is abundant?

A straight line increasing proportionally.

A curve showing initial increase then decrease.

A bell-shaped curve.

A curve that plateaus at Vmax.

With abundant substrate, the rate of reaction increases linearly with enzyme concentration.

19 / 20

19) A significant decrease in enzyme activity at very low temperatures is primarily due to:

Denaturation of the enzyme.

Competitive inhibition by water molecules.

Reduced kinetic energy of molecules, leading to fewer effective collisions.

Formation of stronger enzyme-substrate bonds.

Low temperature slows molecular motion, reducing collision frequency between enzyme and substrate, thus lowering activity.

20 / 20

20) A molecule that binds to an enzyme and decreases its activity is called an:

Cofactor

Substrate

Inhibitor

Activator

An inhibitor is any substance that reduces the activity of an enzyme. Inhibition can be a normal regulatory mechanism or caused by foreign substances like drugs or poisons.

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Enzymes Test. 4

1 / 12

1) Which type of inhibition involves the inhibitor binding to the enzyme-substrate complex, but not to the free enzyme?

Competitive inhibition

Non-competitive inhibition

Feedback inhibition

Uncompetitive inhibition

Uncompetitive inhibitors bind only to the enzyme-substrate complex, reducing both Vmax and Km of the reaction.

2 / 12

2) Which type of inhibition is often a normal mechanism for regulating metabolic pathways in living organisms?

Competitive inhibition by drugs

Irreversible non-competitive inhibition

Heavy metal inhibition

Feedback inhibition

Feedback inhibition is a natural regulatory process used by cells to control enzyme activity and conserve resources.

3 / 12

3) An enzyme undergoing feedback inhibition typically has:

Only an allosteric site.

Both an active site and an allosteric site.

No specific binding sites.

Only an active site.

Enzymes involved in feedback inhibition have both an active site for the substrate and an allosteric site for the product.

4 / 12

4) Sulfa drugs act as inhibitors of bacterial enzyme action by mimicking PABA (para-aminobenzoic acid), a substrate for folic acid synthesis. This mechanism classifies sulfa drugs as:

Allosteric regulators.

Non-competitive inhibitors.

Competitive inhibitors.

Irreversible inhibitors.

Sulfa drugs mimic PABA and competitively inhibit the enzyme involved in folic acid synthesis in bacteria.

5 / 12

5) Which of the following is an example of a competitive inhibitor mentioned in the provided text?

Penicillin

Cyanide

Threonine

Heavy metal salts

Penicillin blocks the active site of bacterial enzymes involved in cell wall synthesis, making it a competitive inhibitor.

6 / 12

6) In feedback inhibition, the end product typically binds to which site on the enzyme to exert its inhibitory effect?

Active site

Substrate binding site

Allosteric site

Catalytic site

The end product binds to an allosteric site, causing a conformational change that reduces enzyme activity.

7 / 12

7) Feedback inhibition is a regulatory mechanism where the activity of an enzyme in a metabolic pathway is inhibited by:

The end product of the pathway.

An intermediate product of the pathway.

An activator molecule.

A competitive substrate.

In feedback inhibition, the final product of a pathway inhibits an earlier enzyme to regulate production.

8 / 12

8) Cyanide is a potent poison because it acts as an irreversible non-competitive inhibitor of:

Trypsin

Pepsin

Cytochrome oxidase

Amylase

Cyanide binds to cytochrome oxidase in the electron transport chain, blocking cellular respiration and energy production.

9 / 12

9) Irreversible non-competitive inhibitors typically cause permanent inactivation of an enzyme by:

Forming strong covalent bonds with the enzyme.

Increasing the optimal temperature of the enzyme.

Competing for active sites.

Mimicking the substrate structure.

Irreversible non-competitive inhibitors form covalent bonds with the enzyme, leading to permanent structural changes.

10 / 12

10) Malonate is given as an example of an inhibitor of succinate dehydrogenase. It is chemically similar to succinate. What type of inhibition would malonate likely exhibit?

Allosteric inhibition

Irreversible inhibition

Competitive inhibition

Non-competitive inhibition

Malonate resembles succinate and competes for the enzyme's active site, making it a competitive inhibitor.

11 / 12

11) Heavy metal ions like Hg++ and Ag+ can act as non-competitive inhibitors by:

Binding to the active site.

Breaking disulfide bridges and causing enzyme denaturation.

Increasing the enzyme's optimal temperature.

Competing with the substrate for binding.

Heavy metals disrupt enzyme structure by binding to sulfhydryl groups, breaking disulfide bonds and denaturing the enzyme.