BMES 501 Lecture: Bioenergetics and Thermodynamics

A set of vocabulary flashcards covering basic thermodynamics, bioenergetics, cellular energy transformations, and ATP dynamics from BMES 501.

Big Bang

The cosmic event, estimated by updated studies to have occurred about 13,800,000,000 years ago, that initiated the outward movement of matter throughout the universe.

Photosynthesis

The process in plant organelles (chloroplasts) that captures light energy from the sun to create energy carriers and manufacture carbohydrates by fixing carbon dioxide.

Chloroplast

An organelle found in plant cells containing chlorophyll solution that absorbs light energy, excites electrons, generates ATP, and fixes carbon into carbohydrates.

Bioenergetics

The study of the types of energy transformations that occur in living organisms.

Energy

The capacity to change or move something, or the capacity to do work.

First Law of Thermodynamics

The law of conservation of energy stating that energy can neither be created nor destroyed, but can only be converted from one form to another.

Second Law of Thermodynamics

The law stating that the sum of the entropies of a system and its surroundings (the universe) must always tend to increase over time.

Third Law of Thermodynamics

The law stating that a perfectly crystalline solid at absolute zero temperature has an entropy value of zero.

Entropy ($S$)

A thermodynamic quantity measuring disorder or the amount of energy in a system that is unavailable to do work.

Enthalpy ($H$)

The total heat content or potential energy stored within a system, equivalent to the difference between heat energy and work energy.

Gibbs Free Energy Change ($ΔG$)

The change in energy available to do work in a system, calculated using the equation $ΔG = ΔH - T ΔS$.

Exergonic Reaction

An energetically favorable or spontaneous reaction where $ΔH$ is negative and energy is released into the system.

Endergonic Reaction

An energy-absorbing reaction where the change in enthalpy is greater than zero ($ΔH > 0$) and products contain more bond energy than the reactants.

Oxidation

The loss of electrons (or the removal of a complete hydrogen atom containing a proton and an electron) from an atom or molecule.

Reduction

The gain of electrons (or a complete hydrogen atom) by an atom or molecule during a chemical reaction.

Adenosine Triphosphate (ATP)

An activated carrier molecule that powers cellular work, liberating approximately $-7.3\,\text{kcal/mol}$ of free energy upon the hydrolysis of its terminal phosphate group.

Glycolysis

The ancient, pre-mitochondrial pathway in cells that carries out the initial breakdown of sugars into pyruvate to release energy.