Chapter 8 AP BIO

Comprehensive vocabulary flashcards covering cellular bioenergetics, thermodynamics, metabolic pathways, and enzyme function from Chapter 8.

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 that 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

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.

Bioenergetics

(1) The overall flow and transformation of energy in an organism. (2) The study of how energy flows through organisms.

Catabolic Pathway

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

Catalyst

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

Chemical Energy

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

Coenzyme

An organic molecule serving as a cofactor. Most vitamins function as coenzymes in metabolic reactions.

Cofactor

Any nonprotein molecule or ion that is required for the proper functioning of an enzyme. Cofactors can be permanently bound to the active site or may bind loosely and reversibly, along with the substrate, during catalysis.

Competitive Inhibitor

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

Endergonic Reaction

A nonspontaneous chemical reaction in which free energy is absorbed from the surroundings.

Energy Coupling

In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction.

Entropy

A measure of molecular disorder, or randomness.

Enzyme

A macromolecule serving as a catalyst, a chemical agent that increases the rate of a reaction without being consumed by the reaction. Most enzymes are proteins.

Enzyme-Substrate Complex

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

Exergonic Reaction

A spontaneous chemical reaction in which there is a net release of free energy.

Feedback Inhibition

A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.

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 free energy of a system ($\Delta G$) is calculated by the equation $\Delta G = \Delta H - T\Delta S$, where $\Delta H$ is the change in enthalpy (in biological systems, equivalent to total energy), $\Delta T$ is the absolute temperature, and $\Delta S$ is the change in entropy.

Induced Fit

Caused by entry of the substrate, the change in shape of the active site of an enzyme so that it binds more snugly to the substrate.

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 either builds a complex molecule (anabolic pathway) or breaks down a complex molecule to simpler molecules (catabolic pathway).

Metabolism

The totality of an organism's chemical reactions, consisting of catabolic and anabolic pathways, which 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.

Phosphorylated Intermediate

A molecule (often a reactant) with a phosphate group covalently bound to it, making it more reactive (less stable) than the unphosphorylated molecule.

Potential Energy

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

Substrate

The reactant on which an enzyme works.

Thermal Energy

Kinetic energy due to the random motion of atoms and molecules; energy in its most random form. See also heat.