- acetyl CoA
- the combination of an acetyl group derived from pyruvic acid and coenzyme A which is made from pantothenic acid (a B-group vitamin)
- activation energy
- the amount of initial energy necessary for reactions to occur
- active site
- a specific region on the enzyme where the substrate binds
- allosteric inhibition
- the mechanism for inhibiting enzyme action in which a regulatory molecule binds to a second site (not the active site) and initiates a conformation change in the active site, preventing binding with the substrate
- anabolic
- describes the pathway that requires a net energy input to synthesize complex molecules from simpler ones
- anaerobic cellular respiration
- the use of an electron acceptor other than oxygen to complete metabolism using electron transport-based chemiosmosis
- ATP
- (also, adenosine triphosphate) the cell’s energy currency
- ATP synthase
- a membrane-embedded protein complex that regenerates ATP from ADP with energy from protons diffusing through it
- bioenergetics
- the concept of energy flow through living systems
- catabolic
- describes the pathway in which complex molecules are broken down into simpler ones, yielding energy as an additional product of the reaction
- chemiosmosis
- the movement of hydrogen ions down their electrochemical gradient across a membrane through ATP synthase to generate ATP
- citric acid cycle
- a series of enzyme-catalyzed chemical reactions of central importance in all living cells that harvests the energy in carbon-carbon bonds of sugar molecules to generate ATP; the citric acid cycle is an aerobic metabolic pathway because it requires oxygen in later reactions to proceed
- competitive inhibition
- a general mechanism of enzyme activity regulation in which a molecule other than the enzyme’s substrate is able to bind the active site and prevent the substrate itself from binding, thus inhibiting the overall rate of reaction for the enzyme
- electron transport chain
- a series of four large, multi-protein complexes embedded in the inner mitochondrial membrane that accepts electrons from donor compounds and harvests energy from a series of chemical reactions to generate a hydrogen ion gradient across the membrane
- endergonic
- describes a chemical reaction that results in products that store more chemical potential energy than the reactants
- enzyme
- a molecule that catalyzes a biochemical reaction
- exergonic
- describes a chemical reaction that results in products with less chemical potential energy than the reactants, plus the release of free energy
- feedback inhibition
- a mechanism of enzyme activity regulation in which the product of a reaction or the final product of a series of sequential reactions inhibits an enzyme for an earlier step in the reaction series
- fermentation
- the steps that follow the partial oxidation of glucose via glycolysis to regenerate NAD+; occurs in the absence of oxygen and uses an organic compound as the final electron acceptor
- glycolysis
- the process of breaking glucose into two three-carbon molecules with the production of ATP and NADH
- heat energy
- the energy transferred from one system to another that is not work
- in vitro
- taking place in a test tube, culture dish, or elsewhere outside a living organism
- kinetic energy
- the type of energy associated with objects in motion
- metabolism
- all the chemical reactions that take place inside cells, including those that use energy and those that release energy
- noncompetitive inhibition
- a general mechanism of enzyme activity regulation in which a regulatory molecule binds to a site other than the active site and prevents the active site from binding the substrate; thus, the inhibitor molecule does not compete with the substrate for the active site; allosteric inhibition is a form of noncompetitive inhibition
- oxidative phosphorylation
- the production of ATP by the transfer of electrons down the electron transport chain to create a proton gradient that is used by ATP synthase to add phosphate groups to ADP molecules
- potential energy
- the type of energy that refers to the potential to do work
- substrate
- a molecule on which the enzyme acts
- thermodynamics
- the science of the relationships between heat, energy, and work