Metabolism & Enzyme Fundamentals

Vocabulary flashcards reviewing metabolic pathways, forms of energy, thermodynamic laws, ATP structure and function, and mechanisms of enzyme action and regulation.

Catabolic pathway

A metabolic pathway that breaks down molecules and releases energy.

Anabolic pathway

A metabolic pathway that builds complex molecules and consumes energy.

Kinetic energy

Energy associated with the motion of objects or molecules.

Potential energy

Stored energy that results from an object's position or structure.

Thermal energy

Kinetic energy due to random motion of atoms or molecules; heat.

Chemical energy

Potential energy stored in the bonds of molecules.

First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed from one form to another.

Second Law of Thermodynamics

Every energy transfer or transformation increases the entropy (disorder) of the universe.

Exergonic reaction

A spontaneous chemical reaction that releases free energy.

Endergonic reaction

A non-spontaneous chemical reaction that requires an input of free energy.

ATP (adenosine triphosphate)

Cellular energy currency composed of adenine, ribose, and three phosphate groups.

Phosphorylation

Transfer of a phosphate group from ATP to another molecule, powering cellular work.

ATP regeneration

Re-forming ATP by adding a phosphate to ADP using energy from catabolic reactions.

Enzyme

A biological catalyst that speeds up reactions by lowering activation energy.

Active site

Region of an enzyme where the substrate binds and the reaction occurs.

Enzyme specificity

The tendency of an enzyme to catalyze only one (or a few) particular reactions due to its active-site shape.

Cofactor

A non-protein, inorganic or organic helper (e.g., metal ion) required for enzyme activity.

Coenzyme

An organic cofactor, often vitamin-derived, that assists enzyme function.

Competitive inhibition

Inhibition in which an inhibitor competes with the substrate for binding at the active site.

Noncompetitive inhibition

Inhibition in which an inhibitor binds away from the active site, altering enzyme shape and function.

Allosteric regulation

Control of enzyme activity by binding a regulator at a site other than the active site, changing enzyme conformation.

Feedback inhibition

Regulation in which the end product of a metabolic pathway inhibits an earlier step to prevent overproduction.

Factors affecting enzyme activity

Temperature, pH, cofactors, and coenzymes influence the rate of an enzyme-catalyzed reaction.