L13 Boltzmann distribution Flashcards
What is the boltzmann distribution?
It’s a probability distribution that describes the distribution of particles among different energy states at a given temperature
In simpler terms, it tells us how likely it is for a particle to have a certain amount of energy
What does each symbol mean p ∝ e^(-E/kT)?
P - probability of having an energy of PE
E - energy of the state
K - Boltzmann constant
T - temperature in kelvin
K - 1.38 x 10^-23 J/K
What is kBT?
Kinetic energy of a molecule is typically described by the boltzmann energy, where:
kB is Boltzmann constant
T is temperature in kelvin
What happens to the bonds when a protein-ligand complex (molecule) is immersied in water?
It is constantly bombarded by water molecules. These collisions can provide enough energy to disrupt weak interactions within the complex, such as hydrogen bonds or van der Waals forces
Explain whether, an interation is strong or weak in terms of the likelihood of a collision with water disrupting it
The strength of an interaction between molecules determines its susceptibility to disruption by water
Weak interactions: Hydrogen bonds, van der waals forces, hydrophobic interactions
Strong interactions: covalent bonds
Explain how the PE change on disrupting a number of interactions can be calculated form the PE change of disrupting each of the interaction
When multiple interactions contribute to the overall potential energy of a system, the total potential energy change upon disrupting all these interactions is simply the sum of the individual potential energy changes.
So add all the potential energy change
Explain why the folded state should always be more stable than the unfolded, if you only think of the potential energy
Folded state is more stable due to the formation of numerous non-covalent interactions
Lower PE
What does it mean to have a lower PE?
Lower potnetial energy state signifies a more stable configuration
Define macrostates and microstates in the context of protein
folding
A macrostate - Particular folded or unfolded state of the protein
A microstate - A specific spatial arrangement of the protein’s atoms that corresponds to the folded state
Explain why there are many more unfolded microstates than
folded microstates, and why this leads to protein unfolding at higher temperatures
At higher temperatures, the molecules in the system gain more kinetic energy. This increased energy can disrupt the stabilising interaction that hold the protein in its folded state
Why is it that the most likely macrostate in a given system will depend on a balance between the likelihood of the individual microstates?
The most likely macrostate in a given is the one that corrseponds to the higher number of microstates
What is the relationship between entropy and microstates?
A system with a larger number of possible microstates has a higher entropy. This is because there are more ways for the system to arrange itself, leading to greater disorder
What is the significance of ∆G being negative, zero or positive for a process?
Negative - Releases energy - favourable
Positive - Requires an input of energy - unfavourable
Zero - system is at equilibrium
Write down the equation for the equilibrium constant K for reversible reactions with 2 products and reactants
K = ([C]^c * [D]^d) / ([A]^a * [B]^b)
What is the formula for Gibbs free energy?
ΔG = ΔH - TΔS
ΔG: Change in Gibbs free energy
ΔH: Change in enthalpy (heat energy)
T: Temperature in Kelvin
ΔS: Change in entropy (disorder)
