User Contributed Dictionary
Translations
- 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.
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.
Overview
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.References
Additional reading
- "Bioenergetics: The Molecular Basis of Biological Energy Transformations (2nd Edition)" by Albert L. Lehninger. Publisher: Addison-Wesley (1971)
- "Bioenergetics (3rd Edition)" by David G. Nicholls and Stuart J. Ferguson. Publisher: Academic Press (2002)
- Universal energy principle of biological systems and the unity of bioenergetics by D E Green and H D Zande in Proceedings of the National Academy of Sciences U S A (1981) Volume 78 pages 5344–5347.
External links
- The Molecular & Cellular Bioenergetics Gordon Research Conference (see).
bioenergetics in Serbian:
Биоенергетика