6 Metabolism

Activation energy

Energy necessary for reactions to occur.

Active site

Enzyme's specific region to which the substrate binds.

Allosteric inhibition

Inhibition by a binding event at a site different from the active site, inducing a conformational change and reducing the enzyme's affinity for its substrate.

Anabolic

Pathways that require an energy input to synthesize complex molecules from simpler ones.

ATP

Adenosine triphosphate, the cell’s energy currency.

Bioenergetics

Study of energy flowing through living systems.

Catabolic

Pathways in which complex molecules break down into simpler ones.

Chemical energy

Potential energy in chemical bonds that releases when those bonds are broken.

Coenzyme

Small organic molecule, such as a vitamin or its derivative, required to enhance an enzyme's activity.

Cofactor

Inorganic ion, such as iron and magnesium ions, required for optimal enzyme activity regulation.

Competitive inhibition

Type of inhibition in which the inhibitor competes with the substrate molecule by binding to the enzyme's active site.

Denature

Process that changes a substance's natural properties.

Endergonic

Describes chemical reactions that require energy input.

Energy coupling

Process during which energy released by one reaction is used to drive another reaction.

Enthalpy

A system's total energy.

Entropy (S)

Measure of randomness or disorder within a system.

Exergonic

Describes chemical reactions that release free energy.

Feedback inhibition

A product's effect of a reaction sequence to decrease its further production by inhibiting the first enzyme's activity in the pathway that produces it.

Free energy

Gibbs free energy is the usable energy, or energy that is available to do work.

Heat

Energy transferred from one system to another that is not work (energy of the molecules' motion or particles).

Heat energy

Total bond energy of reactants or products in a chemical reaction.

Induced fit

Dynamic fit between the enzyme and its substrate, where both components modify their structures for ideal binding.

Kinetic energy

Energy type that takes place with objects or particles in motion.

Metabolism

All the chemical reactions that take place inside cells, including anabolism and catabolism.

Phosphoanhydride bond

Bond that connects phosphates in an ATP molecule.

Potential energy

Energy type that has the potential to do work; stored energy.

Substrate

Molecule on which the enzyme acts.

Thermodynamics

Study of energy and energy transfer involving physical matter.

Transition state

High-energy, unstable state occurring during a chemical reaction, an intermediate form between the substrate and the product.