A Simple Thought Experiment Just think of the biochemistry that occurs when one E. coli cells becomes one billion cells in 48 hours from simple material contained in a solution.
Driving Forces for Natural Processes Enthalpy Tendency toward lowest energy state Form stablest bonds Entropy Tendency to maximize randomness Energy and order.
Enthalpy and Bond Strength Enthalpy = ∆H = heat change at constant pressure Units cal/mole or joule/mole 1 cal = 4.18 joule Sign ∆H is negative for a reaction that liberates heat Heat is a form of energy.
Entropy and Randomness This goes against the grain; must supply lots of energy to take 153 free amino acids and convert them into the ordered sequence that is in myoglobin.
Entropy and Randomness Entropy = S = measure of randomness cal/deg·mole T∆S = change of randomness For increased randomness, sign is “+” Order versus randomness. Just think of the energy input that is required to convert the random biochemical facts in your mind into a metabolic chart - don’t let entropy overcome you.
“System” Definition If your brain is a closed, you can not gain knowledge. Consider how your attitude influences what you can do.
“System” Definition When isolated, you can exchange energy.
“System” Definition When open, both mass and energy are exchanged in a system.
Cells and Organisms: Open Systems Material exchange with surroundings Fuels and nutrients in (glucose) By-products out (CO2) Energy exchange Heat release (fermentation) Light release (fireflies) Light absorption (plants) Life occurs in an open system.
1st Law of Thermodynamics Energy is conserved, but transduction is allowed Transduction Energy is conserved; can change forms.
2nd Law of Thermodynamics In all spontaneous processes, total entropy of the universe increases Randomness increase. A fact of life, just look on how messy your room gets.
2nd Law of Thermodynamics ∆Ssystem + ∆Ssurroundings = ∆Suniverse > 0 A cell (system) can decrease in entropy only if a greater increase in entropy occurs in surroundings C6H12O6 + 6O2 6CO2 + 6H2O complex simple Balanced equation.
Entropy: A More Rigorous Definition From statistical mechanics: S = k lnW k = Boltzmann constant = 1.3810–23 J/K W = number of ways to arrange the system S = 0 at absolute zero (-273ºC) Definition.
Gibbs Free Energy Unifies 1st and 2nd laws ∆G ∆G = ∆H – T∆S Useful work available in a process ∆G = ∆H – T∆S ∆H from 1st law Kind and number of bonds T∆S from 2nd law Order of the system Gibbs free energy connects the first and second laws of thermodynamics.