1. Energy The ultimate source of all energy on Earth

2. The Addition of Energy was important in early chemical evolution Energy = the capacity to do work –Potential energy = stored energy –Kinetic energy = energy of motion –Other types of energy = thermal, sound, mechanical, light, etc.

3. 3. When the molecule strikes the rocks below, its kinetic energy is converted to thermal, mechanical, and sound energy. 1. A water molecule sitting at the top of a waterfall has a defined amount of potential energy, E p. 2. As the molecule falls, this stored energy is converted to kinetic energy, E k. Mechanical energy Heat Sound E p (lower) EkEk E p (higher) ENERGY TRANSFORMATION IN A WATERFALL

4. Newton’s First Law of Thermodynamics Energy is never created or destroyed, it is converted from one form to another The total amount of energy in a closed system remains the same

5. Newton’s Second Law of Thermodynamics In a closed system, energy will transformation will always occur so that the entropy of the system will increase Entropy = random, useless energy that cannot do work, disorder, randomness

6. Newton’s Second Law of Thermodynamics Living organisms are highly ordered

7. Spontaneous changes within a system will occur to increase the entropy and free energy in a system G = the quantity of energy in a system that can perform work ∆G = G final state - G starting state

8. How do chemical reactions occur? Chemical reactions = the formation and breaking of chemical bonds: Reactant + Reactant  Products AB + CD  AC + BD When the forward and back reactions occur at the same rate, the system is stable and is called a chemical equilibrium

9. Example of an exergonic reaction: Burning methane H H C HH C OOOOO HH Energy 2 Water Carbon dioxide Oxygen Methane Exergonic reactions release energy and occur spontaneously

10. High-energy photon H H HO O OOC C Endergonic reactions require the addition of energy Energy + H 2  H + H Energy + CO 2  CO + O

11. Energy changes in exergonic and endergonic reactions

12. Free energy in chemical reactions The amount of free energy in a system depends on the entropy, temperature of the system: G = H - TS The change in energy in a system is: ∆G = ∆H - T ∆GS

13. To do work and power endergonic reactions, cells use ATP

14. Coupling of exergonic and endergonic reactions

15. ATP is regenerated continuously (cell respiration)