Chapter 4 - Enzymes and Energy (Video)

Vocabulary flashcards covering key terms and concepts from the notes on enzymes and energy.

Genetic disorder

A condition caused by genetic mutation that impairs production of certain proteins.

Enzyme

A biological catalyst, usually a protein, that speeds reactions by lowering activation energy and is not consumed.

Substrate

The molecule that binds to an enzyme's active site and is converted during the reaction.

Product

The molecule(s) formed from the substrate(s) after catalysis.

Catalyst

Substance that increases the rate of a chemical reaction without being consumed; in biology, typically an enzyme.

Activation energy

Minimum energy required to start a reaction; catalysts lower this energy barrier.

Reversible reaction

A reaction that can proceed in both forward and reverse directions.

Irreversible reaction

A reaction that proceeds predominantly in one direction with a large energy change.

Law of mass action

In a reaction, rates depend on the concentrations of reactants; in enzyme reactions, substrate concentration affects rate.

Carbonic anhydrase (example)

Enzyme-catalyzed reaction H2O + CO2 ↔ H2CO3, illustrating reversible, mass-action dynamics.

Induced fit model

Model where an enzyme changes shape to better accommodate the substrate, enhancing catalysis.

Lock-and-key model

Model where the enzyme's active site fits only a specific substrate with little shape change.

Active site

The region of the enzyme where the substrate binds and catalysis occurs.

Enzyme specificity

The property that an enzyme catalyzes a particular reaction or binds specific substrates.

pH effect on enzymes

Enzymes have an optimal pH; deviations alter enzyme shape and activity.

Substrate concentration

Amount of substrate available; higher concentration increases rate until enzymes saturate.

Enzyme concentration

Amount of enzyme present; higher concentration increases rate until substrate is limiting.

Enzyme activation

Processes that activate enzymes, such as zymogen activation and phosphorylation.

Zymogen

An inactive enzyme precursor that must be activated to become functional.

Phosphorylation

Addition of a phosphate group to an enzyme, often regulating activity.

Dephosphorylation

Removal of a phosphate group, often altering or reducing enzyme activity.

Turnover (enzymes)

Synthesis and degradation cycle of enzymes; enzymes can be reactivated or replaced as needed.

Cofactor

Inorganic ion bound to an enzyme to aid catalysis (e.g., Ca2+, Mg2+).

Coenzyme

Organic molecule, often vitamin-derived, that assists enzyme-catalyzed reactions.

Coenzymes derived from vitamins

Most coenzymes come from water-soluble vitamins.

Metabolic pathway

A linked sequence of enzyme-catalyzed reactions from initial substrate to final product.

End-product inhibition

Negative feedback where the final product inhibits the rate-limiting enzyme.

Endergonic

Reactions that require an input of energy.

Exergonic

Reactions that release energy.

Adenosine triphosphate (ATP)

Universal energy carrier; energy stored in P–P bonds; ATP hydrolysis drives work in the cell.

ATP hydrolysis

Exergonic reaction that releases energy to power endergonic cellular processes.

Nicotinamide adenine dinucleotide (NAD/NAD+ and NADH)

Electron carrier; NAD+ accepts electrons to become NADH during oxidation-reduction reactions.

Flavin adenine dinucleotide (FAD/FADH2)

Electron carrier; FAD accepts electrons to become FADH2 in redox reactions.

NADH

Reduced form of NAD; carries electrons to the electron transport chain.

FADH2

Reduced form of FAD; donates electrons to the electron transport chain.

Oxidation

Loss of electrons in a redox reaction.

Reduction

Gain of electrons in a redox reaction.

Redox reaction

A coupled oxidation–reduction reaction transferring electrons between molecules.

Proton gradient

Diffusion-driven force generated by differing H+ concentration across a membrane, used to synthesize ATP.

Mitochondria

Organelle where most ATP is produced; contains inner membrane with proton gradient.

Bioenergetics

Study of energy flow and transformation in living systems.

First Law of Thermodynamics

Energy cannot be created or destroyed; it can only be transformed, often with some energy lost as heat.

Kinetic energy

Energy of motion.

Potential energy

Stored energy, such as chemical bonds or gradients.