Enzymes - AP Biology

Define the term 'apoenzyme'.

Inactive enzyme lacking its cofactor. Requires cofactor binding to become catalytically active.
Identify the term for the protein component of an enzyme without its cofactor.

Apoenzyme. The protein part that needs cofactors to become fully functional.
Which term describes enzymes that remain unchanged after a reaction?

Reusable. Enzymes are not consumed and can catalyze multiple reaction cycles.
What effect does enzyme concentration have on reaction rate?

Increases rate until substrate saturation. More enzymes mean more active sites until all substrate is bound.
What is the primary function of enzymes in biological systems?

Catalysts that lower activation energy of reactions. They speed up reactions by reducing the energy barrier needed to start them.
What is the term for a non-protein molecule aiding enzyme function?

Cofactor. Inorganic helper molecule essential for proper enzyme function.
Which factor does not affect enzyme activity: temperature, pH, or light?

Light. Light doesn't directly affect enzyme structure or chemical activity.
Identify the term for enzyme helpers that are small organic molecules.

Coenzymes. Organic molecules like vitamins that assist in enzyme catalysis.
What is the role of an allosteric site in enzyme regulation?

Site for non-competitive inhibitors or activators. Regulatory binding site separate from the active site.
What is the effect of non-competitive inhibitors on $V_{max}$ ?

Decreases $V_{max}$ . Cannot reach the same maximum rate as uninhibited enzyme.
Which term describes the enzyme-substrate complex transition state?

Transition state. High-energy intermediate formed during the enzyme-catalyzed reaction.
Identify the type of inhibition where an inhibitor binds to the active site.

Competitive inhibition. Inhibitor competes with substrate for the same binding site.
What does 'substrate saturation' refer to in enzyme kinetics?

Point where increasing substrate does not increase rate. All enzyme active sites are occupied, creating maximum reaction rate.
What is the effect of enzyme concentration on reaction rate if substrate is limited?

No effect. Substrate becomes the limiting factor, not enzyme availability.
What is the result of enzyme denaturation?

Loss of structure and function. Heat or pH extremes unfold the protein, destroying active site shape.
What is the effect of temperature on enzyme activity?

Increases activity up to an optimal point; then decreases. Heat increases molecular motion but denatures enzymes at extreme temperatures.
Which part of the enzyme is altered during feedback inhibition?

Allosteric site. End product binds here to inhibit the enzyme that produces it.
Identify the part of the enzyme where substrate molecules bind.

Active site. This binding region has a specific shape complementary to the substrate.
Which term describes the specific 3D arrangement of an enzyme?

Conformation. 3D shape determines function and substrate binding specificity.
What is the primary factor determining enzyme specificity?

Shape of the active site. Complementary shape between active site and substrate ensures selectivity.
What is the role of a coenzyme in enzyme activity?

Organic cofactor aiding enzyme function. Works as a temporary carrier of atoms or functional groups.
What is the primary structural unit of an enzyme?

Amino acids. Linked amino acids form the backbone of all enzyme structures.
Which molecule acts as a common coenzyme in redox reactions?

NAD+. Essential electron carrier in cellular respiration and metabolism.
Identify the term for a molecule that decreases enzyme activity.

Inhibitor. Reduces enzyme function through competitive or non-competitive mechanisms.
Which enzyme catalyzes the breakdown of hydrogen peroxide?

Catalase. Converts toxic $H_2O_2$ into harmless water and oxygen.
Identify the term for enzymes with multiple forms that catalyze the same reaction.

Isozymes. Different enzyme variants that perform the same catalytic function.
What type of macromolecule are enzymes typically classified as?

Proteins. Made of amino acid chains folded into specific 3D structures.
What happens to enzyme activity when pH is altered from optimal?

Activity decreases. pH changes alter enzyme shape and charge distribution at the active site.
Which enzyme is responsible for breaking down proteins?

Protease. Cleaves peptide bonds in proteins during digestion.
What is the term for a reaction rate plateau despite increased substrate?

Saturation. Maximum rate reached when all enzymes are working at full capacity.
What is the effect of competitive inhibitors on $K_m$ ?

Increases $K_m$ . Requires higher substrate concentration to reach half-maximal velocity.
State the effect of a non-competitive inhibitor on enzyme activity.

Reduces activity regardless of substrate concentration. Binds to allosteric site, changing enzyme shape and reducing function.
Identify an example of an enzyme that operates optimally in acidic conditions.

Pepsin. Functions optimally at stomach pH around 1.5-2.0.
Identify the hypothesis describing enzyme-induced fit with substrates.

Induced fit model. Enzyme slightly changes shape to better accommodate the substrate.
Identify the type of inhibition that is reversible by increasing substrate concentration.

Competitive inhibition. Adding more substrate can overcome this type of inhibition.
What is the term for the minimum energy required to start a reaction?

Activation energy. Energy barrier that enzymes lower to speed up reactions.
Name an enzyme that breaks down starch into sugar.

Amylase. Breaks down starch into maltose and glucose for energy.
What is the function of a prosthetic group in enzyme activity?

Tightly bound cofactor aiding enzyme function. Permanently attached cofactor that's part of the enzyme structure.
Which term describes the enzyme's specificity to its substrate?

Lock and key model. Describes how enzyme shape perfectly matches its specific substrate.

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