Energy, Chemical Reactions and Cellular Respiration

Vocabulary flashcards covering major terms from the lecture on energy, chemical reactions, enzymes, and cellular respiration.

Potential Energy

Stored energy related to position or condition

Kinetic Energy

Energy of motion

Chemical Energy

Potential energy held in chemical bonds of molecules

Electrical Energy

Kinetic energy from movement of charged particles (ions, electrons)

Mechanical Energy

Energy displayed by objects in motion due to an applied force

Sound Energy

Energy from compression of molecules by a vibrating object

Radiant Energy

Energy carried by electromagnetic waves, e.g., visible light

Heat

Random kinetic energy of atoms/ions; measured as temperature and usually unusable for work

First Law of Thermodynamics

Energy cannot be created or destroyed—only transformed

Second Law of Thermodynamics

Energy transformations lose usable energy as heat

Metabolism

Sum total of all biochemical reactions in living cells

Catabolism

Collective decomposition (breakdown) reactions in the body

Anabolism

Collective synthesis (building) reactions in the body

Reactant

Substance present before a chemical reaction; written on the left side of an equation

Product

Substance formed by a chemical reaction; written on the right side

Decomposition Reaction

Reaction that breaks a large molecule into smaller ones (AB → A + B)

Synthesis Reaction

Reaction combining two or more substances to make a larger one (A + B → AB)

Exchange Reaction

Reaction in which atoms/groups are swapped between molecules (AB + C → A + BC)

Oxidation-Reduction (Redox) Reaction

Exchange reaction involving transfer of electrons; oxidation loses, reduction gains electrons

Exergonic Reaction

Reaction that releases energy; reactants have more energy than products

Endergonic Reaction

Reaction that requires energy input; products store more energy than reactants

Irreversible Reaction

Chemical reaction that proceeds in one direction with net loss of reactants

Reversible Reaction

Reaction that can proceed both directions and reach equilibrium

Enzyme

Biological catalyst that lowers activation energy and accelerates reactions

Activation Energy

Minimum energy barrier that must be overcome for a reaction to begin

Induced Fit Model

Concept that enzyme changes shape to fit substrate more snugly during catalysis

ATP Cycling

Continuous formation and breakdown of ATP between ATP and ADP + Pi

ATP (Adenosine Triphosphate)

Cell’s immediate energy currency used to power work

Cellular Respiration

Process that uses O₂ to convert glucose into ATP, CO₂, and H₂O

Glycolysis

Anaerobic cytosolic breakdown of glucose to 2 pyruvate yielding 2 ATP

Pyruvate Oxidation (Intermediate Stage)

Conversion of pyruvate to acetyl CoA in mitochondria producing CO₂ and NADH

Citric Acid (Krebs) Cycle

Mitochondrial cycle oxidizing acetyl CoA to generate CO₂, NADH, FADH₂, and 2 ATP

Electron Transport System

Mitochondrial membrane chain using electrons from NADH/FADH₂ to drive oxidative phosphorylation

Substrate-Level Phosphorylation

Direct ATP formation by transferring phosphate from a substrate to ADP

Oxidative Phosphorylation

ATP synthesis powered by electron transport and oxygen-dependent chemiosmosis

NAD⁺

Coenzyme that accepts electrons to become NADH during redox reactions

NADH

Reduced form of NAD⁺ that carries high-energy electrons to the electron transport chain

FADH₂

Reduced coenzyme (from FAD) delivering electrons to the electron transport chain

Acetyl CoA

Two-carbon molecule bound to coenzyme A that enters the citric acid cycle

Lactate (Lactic Acid)

Product formed from pyruvate under low O₂ to regenerate NAD⁺ for glycolysis

Beta Oxidation

Pathway that cleaves fatty acids into successive acetyl CoA units for aerobic respiration