Unit 3: Cellular Energetics - Enzyme Structure, Catalysis, and Environmental Impacts

Comprehensive vocabulary flashcards covering enzyme structure, enzyme catalysis, and environmental impacts on enzyme function for AP Biology Unit 3.

Metabolism

The sum of all chemical reactions occurring in a cell or organism.

Metabolic Pathway

A series of chemical reactions that begins with a specific molecule and ends with a product, where each step is catalyzed by a specific enzyme.

Catabolic Pathways

Metabolic pathways that release energy by breaking down complex molecules into simpler compounds, such as cellular respiration breaking down glucose in the presence of oxygen.

Anabolic Pathways

Metabolic pathways that consume energy to build complex molecules from simpler ones, such as the synthesis of a protein from amino acids.

Bioenergetics

The study of how organisms manage their energy resources.

Catalyst

A chemical agent that speeds up a reaction without being consumed by the reaction.

Enzyme

A catalytic protein that accelerates metabolic reactions by lowering activation energy barriers without being consumed.

Substrate

The specific reactant that an enzyme acts upon, possessing a complementary shape, conformation, and charge to its enzyme.

Enzyme-Substrate Complex

A temporary complex formed when an enzyme binds to its complementary substrate molecule.

Active Site

The specific pocket or region on an enzyme where the substrate binds to undergo catalysis.

Induced Fit

The conformational adjustment of an enzyme's active site around the substrate that brings chemical groups into positions that enhance catalytic ability.

Activation Energy ($E_A$)

The initial free energy required to start a chemical reaction, often supplied as thermal energy absorbed by reactant molecules from their surroundings.

Endergonic Reaction

A non-spontaneous chemical reaction requiring a net input of energy, associated with a positive change in free energy ($\Delta G$).

Exergonic Reaction

A chemical reaction that results in a net release of energy, associated with a negative change in free energy ($\Delta G$).

Denaturation

The process by which an enzyme loses its native secondary and tertiary structures due to disruptions in $H$-bonds from extreme environmental factors (such as pH or temperature), rendering it biologically inactive.

Negative Feedback

A regulatory mechanism in which the end product of a metabolic pathway inhibits an upstream process responsible for its production, preventing waste of energy and resources.

Competitive Inhibitor

A substance that reduces enzyme activity by binding directly to the active site, competing with the substrate for access.

Noncompetitive Inhibitor

A substance that impedes enzymatic reactions by binding to an allosteric site rather than the active site, inducing a conformational change that reduces active site effectiveness.

Allosteric Regulation

The modification of an enzyme's activity occurring when a regulatory molecule binds to a protein at one site and influences its structure and function at a distinct site, resulting in either inhibition or stimulation.

Cofactors

Inorganic atoms or molecules that assist enzymes in carrying out catalysis.

Coenzymes

Organic molecules that assist enzymes during catalysis; a specialized subcategory of cofactors.