Metabolism Vocab

Activation energy

The amount of energy that reactants must absorb before a chemical reaction will start; also called free energy of activation.

Active site

The specific region of an enzyme that binds the substrate and forms the pocket in which catalysis occurs.

Allosteric regulation

The binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site.

Anabolic pathway

A metabolic pathway that consumes energy to synthesize a complex molecule from simpler molecules.

ATP (adenosine triphosphate)

An adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed; this energy is used to drive endergonic reactions in cells.

Catabolic pathway

A metabolic pathway that releases energy by breaking down complex molecules into simpler molecules.

Catalysis

A process by which a chemical agent called a catalyst selectively increases the rate of a reaction without being consumed by the reaction.

Catalyst

A chemical agent that selectively increases the rate of a reaction without being consumed by that reaction.

Chemical energy

Energy available in molecules for release in a chemical reaction; a form of potential energy.

Competitive inhibitor

A substance that reduces the activity of an enzyme by entering the active site in place of the substrate, whose behavior it mimics.

Enzyme

A macromolecule serving as a catalyst, increasing the rate of a reaction without being consumed; most enzymes are proteins.

enzyme-substrate complex

A temporary complex formed when an enzyme binds to its substrate molecule(s).

First law of thermodynamics

The principle of conservation of energy; energy can be transferred and transformed, but it cannot be created or destroyed.

Free energy

The portion of a biological system’s energy that can perform work when temperature and pressure are uniform throughout the system; the change in __ of a system is ∆G.

Kinetic energy

The energy associated with the relative motion of objects; moving matter can perform work by imparting motion to other matter.

Metabolic pathway

A series of chemical reactions that builds a complex molecule (anabolic __) or breaks down a complex molecule into simpler ones (catabolic __).

Metabolic rate

The amount of energy an animal uses in a unit of time.

Metabolism

The totality of an organism’s chemical reactions, consisting of catabolic and anabolic pathways that manage the material and energy resources of the organism.

Noncompetitive inhibitor

A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing the enzyme’s shape so that the active site no longer effectively catalyzes the conversion of substrate to product.

Potential energy

The energy that matter possesses as a result of its location or spatial arrangement.

Product

A material resulting from a chemical reaction.

Reactant

A starting material in a chemical reaction.

Second law of thermodynamics

The principle stating that every energy transfer or transformation increases the entropy of the universe; usable forms of energy are at least partially converted to heat.

Substrate

The reactant on which the enzyme works.

Thermodynamics

The study of energy transformations that occur in a collection of matter.