AskDefine | Define bioenergetics

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  1. biology physics The study of the energy transformations that take place in living organisms


  • Italian: bioenergetica

Extensive Definition

This article is about the biological study of energy transformation. For the Reichian body-oriented psychotherapy sometimes known as bioenergetics, see bioenergetic analysis.
Bioenergetics is the subject of a field of biochemistry that concerns energy flow through living systems. This is an active area of biological research that includes the study of thousands of different cellular processes such as cellular respiration and the many other metabolic processes that can lead to production and utilization of energy in forms such as ATP molecules. All biological processes including the chemical reactions of bioenergetics obey the law of thermodynamics.


  • First Law is the conservation of energy: energy can neither be created nor destroyed.
  • Second Law states that the degree of disorder or entropy (S) of a closed system or of the universe as a whole can only increase.


Growth, development and metabolism are some of the central phenomena in the study of biological organisms. The role of energy is fundamental to such biological processes. The ability to harness energy from a variety of metabolic pathways is a property of all living organisms. Life is dependent on energy transformations; living organisms survive because of exchange of energy within and without.
In a living organism chemical bonds are broken and made as part of the exchange and transformation of energy. The chemical bonds in carbohydrates, including sugars, are important for the storage of energy. Other chemical bonds that are important for metabolism include the terminal phosphate bonds of ATP and the energy-rich bonds of fats and oils. These molecules, along with oxygen, are important energy sources for many biological processes. Utilization of chemical energy from such molecules powers biological processes in every biological organism. Bioenergetics is the part of biochemistry concerned with the energy involved in making and breaking of chemical bonds in the molecules found in biological organisms.
Food molecules are sources of chemical energy for many organisms. Not all metabolizable energy is available for the production of ATP.

Types of Reactions

  • Exergonic is a spontaneous reaction that releases energy. It is thermodynamically favored. On the course of a reaction, energy needs to be put in, this activation energy drives the reactants from a stable state to a highly energetic unstable configuration. These reactants are usually complex molecules that are broken into simpler products. The entire reaction is usually catabolic. The release of energy, also called free energy is a - ΔG because energy is lost from the bonds formed by the products.
  • Endergonic is an anabolic reaction that consumes energy. It has a +ΔG because energy is required to break bonds.
The free energy ( ΔG) gained or lost in a reaction can be calculated: ΔG= ΔH - T ΔS.
Also, ΔG = ΔG˚' + 2.303RTlog([P]/[R]) where
    • R is the gas constant, 1.987 cal/mol
    • T is temperature in Kelvin K = 273 + ˚C
    • P is Products
    • R is the reactants

Chemiosmotic theory

One of the major triumphs of bioenergetics is Peter D. Mitchell's chemiosmotic theory of how protons in aqueous solution function in the production of ATP in cell organelles such as mitochondria. Other cellular sources of ATP such as glycolysis were understood first, but such processes for direct coupling of enzyme activity to ATP production are not the major source of useful chemical energy in most cells. Chemiosmotic coupling is the major energy producing process in most cells, being utilized in chloroplasts and many single celled organisms in addition to mitochondria.


Additional reading

External links

  • The Molecular & Cellular Bioenergetics Gordon Research Conference (see).
bioenergetics in Serbian: Биоенергетика
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