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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 (2nd law).
The following formula represents the change of free energy in a system
D G=Gfinal-Ginitial
(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
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Mr. Stanley
Last updated: March 11, 2004