Ch. 5: Energetics of Biological Systems Flashcards
3 ways rate of rxn can be altered?
1) ⬆️ [reactants] (not practical/desirable)
2) ⬆️ temp (not practical)
3) Add catalyst (enzyme) (practical)
What is the 1st law of thermodynamics?
Energy can neither be created nor destroyed
What is the 2nd law of thermodynamics?
Entropy of the system & surroundings ⬆️ & attain max value at equilibrium
Exergonic vs endergonic rxns?
Exergonic: spontaneous, release energy
Endergonic: thermodynamically unfavorable
What is the equation for Gibbs free energy?
🔺G = 🔺H - T(🔺S)
🔺G* < 0 is seen in which type of rxns?
Spontaneous (exergonic) rxns
🔺G* > 0 is seen in which type of rxns?
Non-spontaneous (endergonic) rxn
🔺G* vs 🔺G?
🔺G* = standard free energy change at pH 7
🔺G = change in free energy
If 🔺H is a major contributor to a rxn, what does this mean about the rxn? (Enthalpy driven rxn)
Rxn involves ionic interactions, H bonding (heat has to be changed)
If 🔺S is a major contributor to a rxn, what does this mean about the rxn? (Entropy driven rxn)
Rxn involves hydrophobic/hydrophilic interactions
As Keq ⬆️, what happens to 🔺G*?
🔺G* ⬇️
Tendency for rxns to occur ⬆️ spontaneously
How many high energy bonds does ATP posses?
2
What type of 🔺G* does ATP have?
Large, negative free energy of hydrolysis
Rxn type: A ➡️ B
Rate eqn? Reaction order?
Rate = k[A]
1st order rxn (no collision needed)
Rxn type: A + B ➡️ C + D
Rate eqn? Reaction order?
Rate = k[A][B]
Second order rxn
