Energy and Enzymes in Biological Systems

Thermodynamics

Study of energy transformation in systems

Free Energy

Energy available to do work in a system

Enzymes

Biological catalysts that speed up reactions

Catabolic Reactions

Breakdown reactions releasing energy

Anabolic Reactions

Build-up reactions requiring energy

Phosphatases

Enzymes removing phosphate groups

Kinetic Energy

Energy of movement, e.g., light

Potential Energy

Stored energy, e.g., chemical

First Law of Thermodynamics

Energy can't be created or destroyed, only transformed

Second Law of Thermodynamics

Every energy transfer increases entropy

Entropy

Tendency of energy to disperse in a system

Biological Systems

Transform energy from light and catabolism

Chemical Equilibrium

Balanced reactants and products in a reaction

Exothermic Reaction

Releases heat, products have less thermal energy

Endothermic Reaction

Absorbs heat, products have more thermal energy

Spontaneous Reactions

Occur when products have lower energy and higher entropy

Free Energy (Gibbs)

Energy available for work in a system at uniform temperature

Endergonic Reactions

Energy-absorbing reactions, ΔG > 0

Exergonic Reactions

Energy-releasing reactions, ΔG < 0

Energy Coupling Reactions

Transfer energy from exergonic to endergonic reactions

Equilibrium

Stable state where reactants and products rates are equal

Living Systems

Open systems maintaining organization by energy and matter exchange

Flow of Energy

Transfer of energy through the biosphere

Equilibrium in Living Systems

Stable state in open systems with energy and matter exchange

Metabolism

All chemical reactions in a cell or organism

Catabolic Pathway

Energy released by breaking complex molecules

Anabolic Pathway

Consumes energy to build complex molecules

ATP Hydrolysis

ATP breakdown releasing free energy

Energy Coupling

Linking ATP breakdown energy to reactions

Chemical Energy

Energy stored in chemical bonds

Sources of Energy

Biological systems transform energy from light and chemical breakdown of molecules.

Law of Conservation of Mass

States that mass is conserved in chemical reactions.

Enthalpy

Total potential energy of a system, including heat content and bond types.

Revised Spontaneous Reaction definition

A reaction where the free energy of products is less than that of reactants.

ATP

Adenosine triphosphate, providing free energy for cellular processes.

Activation Energy

The initial energy input required to start a reaction.

Allosteric Regulation

Regulation of enzyme activity by molecules binding to sites other than the active site.

Enzyme Inhibition

Process where molecules inhibit enzyme activity by binding to specific sites.

Temperature and pH

Key factors affecting enzyme activity in biological systems.

Catalyst

Agent that speeds up a reaction without being consumed

Enzyme-Substrate Complex

Temporary combination of enzyme and substrate during a reaction

Biological Catalysts

Substances that speed up reactions without being consumed

Adenosine monophosphate (AMP)

Activates enzyme PFK by binding at a distinct site

Hydrolysis of ATP to ADP and Pi

Exergonic reaction releasing energy

Energy Diagram

Illustrates energy changes in enzyme-catalyzed and uncatalyzed reactions

Active Site

Region on enzyme where substrates bind