Lecture 6. Metabolism Flashcards
What is the first law of thermodynamics?
The total energy of a system and its surroundings is constant. Energy cannot be created or destroyed
What is energy?
The capacity to carry out change
What is change in energy approximately equal to in a biochemical reaction?
The change in enthalpy
What is an exothermic reaction?
Energy is released by the system
What is an endothermic reaction?
Energy is taken up by the system
What is the second law of thermodynamics?
Entropy is always increasing in an isolated system
What is the equation for Gibbs free energy?
ΔG = ΔH - TΔS
ΔG
Change in free energy
ΔH
Change in enthalpy
ΔS
Change in entropy
T
Temperature in Kelvin
What does a -ΔG mean in terms of a reaction?
It means the reaction is spontaneous with a loss of free energy - exergonic
Enthalpy equation
ΔH = ΔE + pΔV
ΔE
Change in energy
p
Pressure
V
Volume
What does a +ΔH mean?
Reaction is endothermic
What does a -ΔH mean?
Reaction is exothermic
What does a -ΔG mean?
The entropy of the universe is increasing
What does a +ΔG mean?
The reaction is unfavourable or not spontaneous - endergonic
ΔG = 0
The system is in equilibrium - dynamic equilibirum
Can living organism achieve overall equilibrium?
No
What reaction is close to equilibrium?
G-6-P ⇌ F-6-P
Does ΔG predict the reaction rates?
No
