Chemical Reactions, Energy, and Enzyme Kinetics

Vocabulary flashcards covering key terms related to chemical reactions, energy forms, enzyme structure, kinetics, and regulation.

Anabolic Reaction

A biosynthetic process in which small molecules assemble into a larger molecule; requires energy input.

Catabolic Reaction

A degradative process in which large molecules are broken into smaller ones; releases energy.

Exergonic Reaction

A spontaneous reaction (−ΔG) that releases free energy.

Endergonic Reaction

A non-spontaneous reaction (+ΔG) that requires an input of free energy.

Kinetic Energy

Energy associated with motion, such as a person jumping.

Potential Energy

Stored energy, exemplified by glycogen reserves.

Enzyme

A biological catalyst, usually a protein (sometimes RNA), that accelerates reactions by lowering activation energy.

Catalyst

A substance that increases reaction rate without being consumed in the process.

Activation Energy (Ea)

The minimum energy barrier that reactants must overcome to form products; lowered by enzymes.

Active Site

The region on an enzyme where the substrate binds and catalysis occurs.

Allosteric Site

A secondary enzyme site where effectors (activators or inhibitors) bind to modulate activity.

Induced Fit Model

Theory stating that enzyme and substrate adjust shapes slightly for optimal catalysis upon binding.

Enzyme-Substrate Complex

Temporary association formed when a substrate binds to an enzyme’s active site.

Substrate Specificity

The selective property that allows an enzyme to recognize and act on one (or a few) substrates.

Ribozyme

An RNA molecule that functions as an enzyme.

Competitive Inhibition

Regulation in which an inhibitor mimics the substrate and binds the active site, increasing Km but leaving Vmax unchanged.

Noncompetitive Inhibition

Regulation in which an inhibitor binds an allosteric site, decreasing Vmax while Km remains the same.

Vmax

The maximum reaction velocity achieved by an enzyme at full substrate saturation.

Michaelis Constant (Km)

The substrate concentration at which reaction velocity is half of Vmax; inversely reflects binding affinity.

Binding Affinity

Strength of the interaction between enzyme and substrate; higher affinity corresponds to lower Km.

ATP (Adenosine Triphosphate)

The primary cellular energy carrier, containing high-energy triphosphate bonds.

ATP Hydrolysis

Exergonic cleavage of ATP to ADP + Pi, releasing energy to drive endergonic reactions.

ATP Phosphorylation

Endergonic formation of ATP from ADP + Pi, storing energy harvested from exergonic processes like the electron transport chain.

Electron Transport Chain

Series of membrane-bound complexes that produce ATP by coupling exergonic electron flow to proton pumping.