Overview of Metabolism

A set of flashcards covering key concepts and terms related to metabolism, energy transformations, thermodynamics, and biochemical pathways.

Metabolism

The totality of an organism's chemical reactions.

1st law of thermodynamics

Energy can be transferred or transformed, but not created nor destroyed; also known as conservation of energy.

2nd law of thermodynamics

Every energy transfer or transformation increases the entropy of the universe; entropy is a measure of disorder.

Kinetic energy

Energy due to movement; all moving objects possess kinetic energy.

Potential energy

Energy that is stored in matter and is not due to movement, such as gravitational energy.

Anabolism

Biosynthetic pathways that require energy input to form complex molecules from simpler compounds; typically endergonic.

Catabolism

Pathways that break down complex molecules into simpler compounds, releasing energy in the process; typically exergonic.

Exergonic reactions

Reactions where Gibbs free energy decreases and are spontaneous, indicated by a negative ∆G.

Endergonic reactions

Reactions where Gibbs free energy increases, are not spontaneous, and require energy input, indicated by a positive ∆G.

Free energy

The energy that can be used to do work; often referred to in terms of Gibbs free energy (G).

Energy coupling

Process where energy released during catabolic reactions is used to drive anabolic reactions.

ATP (Adenosine triphosphate)

A molecule that carries energy within cells; it is produced from ADP and inorganic phosphate during energetic processes.

Enthalpy (H)

Total energy in a system, which can be divided into energy able to do work (G) and energy unable to do work (T*S).

Reversible reactions

Chemical reactions that can proceed in both forward and reverse directions; many metabolic reactions are reversible.

Spontaneous reactions

Reactions that occur without an energy input; commonly occur in isolated systems.