The study of energy transduction within biological systems.

Transduction, in this context, literally is change and bioenergetics considers how energy is changed from one form into another by biological systems. For example, from the energy of photons (kinetic energy) to the reduction of, a.k.a., gain of electrons by atoms such as those in chlorophyll molecules – to energy associated with concentration gradients across lipid bilayers (such as a proton motive force) to the energy in chemical bonds (e.g., C-H bonds in glucose).

The three most prominent biochemical "pathways" considered under the heading of bioenergetics are glycolysis, cellular respiration, and photosynthesis. The most prominent molecule is ATP.

The following is a list of major concepts associated with the science of bioenergetics:

Aerobic respirationADPAnaerobic respirationATPATP synthaseBioenergeticsCalvin cycleCarbon fixationCellular respirationChemiosmosisChemotrophChlorophyllCyclic electron flowDark reaction (of photosynthesis)DeaminationElectrochemical gradientElectron transport chainEnergy couplingFADFADH2FermentationFinal electron acceptorGeneration of proton motive forceGlucose oxidationGlycolysisGlycolysis (stoichiometry)Krebs cycleLight reaction (of photosynthesis)Membrane potentialMetabolic waterMitochondriaNAD+NAD regeneration,  NADHNoncyclic electron flowOxidation of waterOxidative phosphorylationOxidizing agentPhotophosphorylationPhotosynthesisPhotosynthesis (overall reaction)PhotosystemsPhotosystem IPhotosystem IIPhototrophPrimary electron acceptorProton motive forceProton pumpPyruvate oxidationReaction centerRedoxReducing agentReduction of oxygenSubstrate-level phosphorylationZ scheme