1. Energy Exchanges 1st Law of Thermodynamics 2nd Law of Thermodynamics
Energy cannot be created nor destroyed, energy is transferred from one form to another
2nd Law of Thermodynamics
Every energy transfer makes the universe more disordered
Entropy is a measure of this disorder
With every energy transfer, heat is lost
Amt of useful energy is decreased with every transfer
PROBLEM: living organisms are highly ordered to decrease entropy
Question: Do living organisms violate 2nd Law?

2. ANSWER NO Living organism is a closed system
Must consider organism and environment
Living organisms…
Maintain highly ordered structure at expense of increased entropy of surroundings
Take in complex high energy molecule, extract energy, release simpler, low energy molecules (CO2 and H2O) and heat to environment

3. ENERGY EXCHANGES Formula is ΔH = ΔG + TΔS ΔH = change in enthalpy
= change in total energy
= heat of reaction
ΔG = change in free energy (Gibbs)
free energy is usable energy available to do work
TΔS = energy lost to the system
T= Temp. in Kelvin
ΔS = change in entropy

4. Exergonic and Endergonic
During every energy exchange (ΔH) some energy is available to do work (ΔG) and some is lost to the system (TΔS)
Exergonic and Endergonic

5. EXERGONIC REACTIONS Reactants have more energy than products
More ordered to less
Unstable to stable
Downhill reaction
Free energy (ΔG) is released and is negative
Spontaneous
Ex: cellular respiration and digestion
LABEL: R, P, Energy and Time on graph

6. ENDERGONIC REACTIONS Products have more energy than reactants
Less ordered to more
Stable to unstable
Uphill reaction
Free energy absorbed from surroundings
ΔG is positive
Ex: photosynthesis, polymer synthesis
Label: R, P, Energy and Time on graph

7. COUPLED REACTIONS
Energy released from exergonic reaction drives endergonic reaction
Exergonic ΔG = max work that can be done
Endergonic ΔG = min work needed to drive the reaction
When these two values are equal – most efficient

8. ATP Production ATP ADP + Pi Exergonic energy Endergonic energy
From catabolism for cellular work
ΔG = -7.3 kcal/mol
ΔG = +7.3 kcal/mol
ADP + Pi

9. How ATP Works Type of Work Description Mechanical Beating cilia
Muscular contraction
Movement
Transport
Active transport
Pumps (H+ and Na+/K+)
Chemical
Endergonic reactions
Polymerization

10. Coupled Reactions NH2 GLU + NH3 GLU GLU + ATP GLU P NH2
ΔG = +3.4 kcal/mol
Not spontaneous
ΔG = -7.3 kcal/mol
GLU + ATP GLU P
NH2
GLU P NH GLU
ΔG = +3.4 kcal/mol
ΔG = -3.9 kcal/mol
OVERALL RXN= ?