Theme A notes - the energy of life

Theme A: The energy of life

The study of thermodynamic forces for biological reactions

Lecture A1 - Energy in the biosphere and Gibbs energy changes
(page 80-88, 91)

Life requires building blocks and energy




Thermodynamic systems

• Living systems are open systems
• Constants: Pressure, Temperature, Volume
• Variables: Energy, Concentration



Flow of energy and material through the biosphere

, Gibbs free energy changes (pg. 85-87) pg. 91

Second law of thermodynamics – entropy of the universe will tend
to increase




At constant temperature and pressure – Gibbs free energy change




Gibbs energy changes: important points to remember
Measure of energy available from a chemical of physical reaction
• DG value is independent of the pathway or mechanism of
For a favorable process:
the reaction
• DG supplies no information about the rate of a reaction
• Negative DG, DG°, DG’ and DG°’ values indicate only that a
Due to:
reaction will proceed spontaneously (exergonic) but do not
• Energy changes indicate that it will procced at a perceivable rate
• Concentration changes