Chapter 8: Energy, Metabolism, and Thermodynamics

Vocabulary flashcards covering metabolism, pathways, types of energy, thermodynamics laws, spontaneity, and Gibbs free energy from Chapter 8 lecture notes.

Metabolism

The total chemical reactions of an organism, which transforms matter and energy.

Metabolic pathway

A pathway that begins with a specific molecule and ends with a product, where each step is catalyzed by a specific enzyme.

Catabolic pathways

Pathways that release energy by breaking down complex molecules into simpler compounds, also referred to as "downhill reactions" (e.g., hydrolysis, cellular respiration).

Anabolic pathways

Pathways that consume energy to build complex molecules from simpler ones, also referred to as "uphill reactions" (e.g., dehydration synthesis, protein synthesis from amino acids).

Chemical equilibrium

Occurs when forward and reverse reactions proceed at the same rate, resulting in constant quantities of reactants and products without the reactions actually stopping.

Energy

The capacity to do work or supply heat.

Free energy

The energy that is actually available to do work.

Potential energy

Stored energy that has the potential to do something later, where the position of the matter matters.

Kinetic energy

The energy of motion; for molecules, higher kinetic energy corresponds to a higher temperature.

Thermal energy

Kinetic energy resulting from the random movements of atoms or molecules.

Chemical energy

Potential energy stored in chemicals that can be released during a chemical reaction.

First law of thermodynamics

The principle stating that energy cannot be created or destroyed; it can only be transferred or transformed.

Second law of thermodynamics

The principle stating that entropy (disorder/randomness) always increases, as energy naturally spreads out and becomes less organized and useful over time.

Spontaneous reaction

A chemical reaction that, once it gets going, can continue on its own without constantly adding energy.

Entropy ($S$)

A measure of disorder or randomness in a system, determined by how spread out products are.

Gibbs free energy ($G$)

The portion of a living system's energy that can do work when temperature and pressure are uniform, as in a living cell.

Electron potential energy in shells

The principle that electrons have the greatest potential energy in the outermost shells; falling to a closer shell converts potential energy into kinetic energy, releasing heat or light.