Bioenergetics an introduction to biological thermodynamics

Thus far, our discussion has considered the chemical changes which constitute metabolism. We must now introduce some fundamental ideas of bioenergetics. Further details can be found in Chapter 2. 

All molecules have an amount of energy determined mainly by their chemical structure. Metabolism involves chemical change. Inevitably therefore, energy changes always accompany the chemical changes which occur in metabolism. Our understanding of bioenergetics arises from physics and the laws of thermodynamics. 

These three energy terms we have met are related by the following equation  

Rearranging this equation gives AG = AH —TAS, which shows that as entropy increases as a function of temperature, free energy decreases. 

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