3.1 Enzymes

Metabolism

The totality of all enzyme-catalysed reactions that occur within a living organism.

Anabolism

The set of metabolic reactions that build up complex molecules from simpler ones.

Catabolism

The set of metabolic reactions that break down complex molecules into simpler ones.

Enzyme specificity

The characteristic of enzymes that allows them to catalyze specific reactions.

Active site

The region on the surface of the enzyme to which a substrate molecule binds.

Lock and Key model

A model suggesting that the substrate (key) exactly fits the active site of the enzyme (lock).

Induced fit model

A more accepted model stating that an enzyme alters its shape in the presence of a substrate to facilitate a reaction.

Activation energy

The minimum energy needed to initiate a chemical reaction.

Exergonic reactions

Reactions that release energy into the system.

Endergonic reactions

Reactions that absorb energy from their surroundings.

Denaturation

A change to the structure of the active site that negatively affects enzyme function.

Enzyme catalysis

The process by which an enzyme increases the rate of a reaction.

Substrate concentration

The amount of substrate present; can affect the rate of enzyme reactions.

Thermal energy

Energy related to the motion of particles; can be introduced to increase the rate of enzyme reactions.

Inhibitors

Molecules that reduce enzyme-substrate interactions by affecting the active site.