History Of Thermodynamics

An overview of thermodynamics and bioenergetics with respect to biochemistry

Introduction:

Living organisms need energy to stay alive and to grow and all the living organisms have the ability to produce energy to carry out their activities. Energy is converted from one form to another in living organisms for example chemical energy can be converted to heat and kinetic energy and also to light energy in some organisms such as fireflies and some species of fishes.

This creation and utilization of energy is studied in a branch of biology called bioenergetics.

Bioenergetics:

Bioenergetics is the study of energy changes and utilization in living cells. Biological energy conversions obey the laws of thermodynamics.

Living things require a continuous

Laws of thermodynamics:

In thermodynamics a system is referred as that part of the universe which is under observation such as an organism or a reaction vessel whereas the rest of the universe is known as surroundings. A system can either exchange matter or energy with its environment or not. If the system can exchange its energy with the surroundings then it is said to be an open system and if the energy cannot be exchanged then the system is said to be closed.

Living organisms are an example of open systems because they can exchange energy and matter with their surroundings by taking up nutrients, releasing waste products and giving out heat in their

The unit of G is joules per mole or calories per mole.

Living organisms resist a change in their entropy by taking in free energy from their surroundings in the form of sunlight and release an equal amount of energy in the form of heat to the environment.

Application of Gibbs free energy to living systems:

Aerobic organisms get their free energy from glucose by oxidizing glucose with oxygen. The end products of this reaction are carbon dioxide and water which are returned to the surroundings. At the end of this reaction the entropy of the surroundings increases whereas the system i.e. the organism remains in a steady state and its entropy does not change.

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When the number of molecules increase as a result of a chemical reaction then the entropy of the environment increases.

Similarly when a solid substance turns to a liquid or a gas then the entropy of the surroundings increases as well because the movement of molecules in gas and liquids is more free which adds to the randomness of the