Energy & Biological Systems

Energy & Biological Systems

Organisms must utilize energy to live. In order to understand biological activity it is necessary to understand energy and it's relationship with living organisms.
Energy: The capacity to do work.
Laws of energy (Laws of thermodynamics)

• First law of Thermodynamics: Energy cannot be created or destroyed, it can only change in form

• Second Law of Thermodynamics: Every transformation of energy results in the increase of randomized energy of the universe. This randomized energy is energy work cannot b extracted from, it is lost in the proverbial "Cosmic couch", and is known as Entropy.

Free Energy & Biological Systems

• Free Energy: The portion of a system's energy that can perform work when the temperature is uniform throughout that system. (G)

• A system's quantity of free energy can be expressed by the following expression:

G=H-TS

Where:

H=Total amount of energy in the system

T=Temperature in ⁰K

S=Its entropy

• This formula can help us determine if a chemical change happens spontaneously. For a reaction to occur spontaneously, it must reduce the amount of free energy in the system, and convert it to entropy (2^nd law).

The following formula represents the change of free energy in a system

D G=G_final-G_initial

(or)

D G=D H-TD S

For any spontaneous reaction to occur D G must have a negative value. In order for this to occur, either (or both) of two things must occur.

The system must give up energy Lower H value

The system must give up order Higher S value