Thermodynamics and Metabolism

The laws of thermodynamics govern the nature of heat and thermal energy. There are 3 laws of thermodynamics:

·         First Law: In a closed system, the amount of input energy equals total output, thus energy cannot be created nor destroyed.

·         Entropy: Entropy is the measure of chaos and disorder in a system. More disorder implies for higher entropy and vice versa. The law of entropy states that entropy will increase for any process because various forms of waste energy, such as heat will be generated. Thus, the entropy of the universe can never decrease.

·         Third Law: At 0 Kelvins (-273 C), all motions will stop. Therefore, it is the lowest possible temperature and is impossible to reach.

How does the law of entropy relate to metabolism?

Essentially, every process in nature drifts away from order, and towards chaos. Organisms die and decay, stars burn out and this is no difference for metabolic processes. Exergonic reaction release energy, thus increases entropy, while endergonic requires energy and decreases entropy. However, when everything is considered as a big closed system, the entropy will always be increasing. Evidently, metabolism without an exception, also obeys the laws of thermodynamics.