A. Energy is the capacity to do work.

B. Thermodynamics is the study of energy.

C. First Law of Thermodynamics: Energy can be neither created or destroyed, but it can be transformed.

D. Second Law of Thermodynamics: When energy is transformed, not all of it can be used. Disorder (entropy) tends to increase.

E. Potential energy-energy of position or "stored" energy.

F. Kinetic energy-energy of motion.

G. Open and closed systems

1. A system cam be thought of as any defined space.
2. Open systems can gain or lose energy and matter.
3. Closed systems can neither gain nor lose energy or matter.

H. Metabolism- all the chemical reactions that occur within a living cell

I. Anabolic Processes

1. require energy
2. assemble small molecules into big ones
3. dehydration synthesis

J. Catabolic processes

1. release energy
2. break large molecules into small ones
3. hydrolysis

K. H = G + TS

1. H is the total energy in a system
2. G is the free energy in a system
3. T is the temperature in Kelvins
4. S is entropy, representing the usable energy in a system

L. Change in G = change in H - T change in S

1. measures the change of free energy that occurs during a chemical reaction

M. If change in G is negative

1. reactants are less stable than the products
2. reaction is spontaneous
3. reaction is catabolic
4. reaction is exergonic
5. energy is released

N. Cellular respiration

1. C₆H₁₂O₆ + 6O₂ -> 6CO₂ + 6H₂O
2. change in G = -686 Kcal / mole of glucose

O. If change in G is positive,

1. reactants are more stable than products
2. reaction is nonspontaneous
3. reaction is anabolic
4. reaction is endergonic
5. energy is required for reaction to occur

P. Photosynthesis

1. 6CO₂ + 6H₂O -> C₆H₁₂O₆ + 6O₂
2. Change in G = +686 Kcal / mole of glucose

Q. if change in G = 0

1. reaction is at equilibrium
2. no work can be done

R. Metabolic disequilibrium keeps living systems from going to change in G = 0

S. ATP (adenosine triphosphate)

1. ribose, adenine, 3 phosphate groups
2. similar to the nucleotide that has adenine
3. involved in energy coupling
4. ATP + H₂O -> ADP + Pi (change in G = -12 Kcal / mole of ATP under cellular conditions)
5. source of usable energy for cells
6. ADP is recycled to ATP by taking in energy from the environment