Bioenergetics is a multidisciplinary field involving biology, chemistry, and biochemistry that is concerned with the flow of energy through organisms at the cellular level. Different organisms undergo many different processes in the production of energy ranging from photosynthesis in plants to fiber feeding in some protists. All of these lead to cellular respiration, also known as oxidative metabolism, through which individual cells are able to produce usable energy. There are thousands of processes that eventually lead to the production of usable energy in the cells of organisms. Bioenergetics is concerned with understanding how these processes work and how they interact with all of the other energy-production processes in the organism.
Energy is absolutely essential to almost all biological processes from movement to brain function. At the lowest molecular level, this energy is produced through the breaking of chemical bonds, usually the bonds of the molecule adenosine triphosphate, or ATP. Different organisms may produce ATP or other energy-rich molecules in different ways. Some organisms are able to break down inorganic compounds and use the energy and materials gained to produce ATP. For example, plants are able to use the energy from the sun to fuel the processes of cellular respiration that lead to the production of ATP.
These reactions that occur at a molecular level are extremely important to the field of bioenergetics, but they are not the only topics of interest. Bioenergetics is concerned with the entire flow of energy from the molecular level to the actual expenditure of energy. Life and its processes involve a constant and ever-changing flow and exchange of energy. There are three particular processes of particular interest to those studying bioenergetics: growth, development, and metabolism.
Growth involves the reproduction of cells; cells grow and divide to produce new cells. Development refers to the processes through which an organism progresses during its life, from initial conception to final death and decay. Metabolism, through which an organism produces energy during its life, is the way in which an organism maintains life and produces the energy necessary for growth and development. These three essential processes are central to the study of bioenergetics as almost all energy used in biological processes is directly or indirectly aimed at one of these goals.
The terms "bioenergetics" and "bioenergetic analysis" are also sometimes used to describe a form of psychotherapy that encompasses both the mind and the body. The field seeks to address and to interpret the patterns expressed by both the mind and the body to work through various psychological or physical issues. The two uses of the word are not related — the biochemical definition of bioenergetics is distinct from bioenergetic analysis.