Thermodynamics + Properties Of Water Flashcards
Negative delta G means…
Spontaneous / favourable / exergonic reaction
Positive delta H is…
Endothermic - bond making
Positive delta S is…
Disordering of system
What is the Gibbs free energy equation?
Delta G = delta H - T delta S
Where T is in Kelvin
Negative delta S is…
Ordering of system
What are the three main considerations of thermodynamics in biological systems?
Temperature is fixed - 310K in humans
There is a balance of delta S vs delta H terms
Cells are NOT closed/isolated systems. Heat is dispersed
What properties does water’s extensive H-bonding account for?
High surface tension
High heat of vaporisation
Describe water’s affect on ion-ion pairs in biological systems
Water can mask the effect of ion-ion interactions - hence not as strong as bonding in salts.
How does ‘hydrophobic bonding’ work?
Hydrophobic groups are forced together by water molecules to minimise their disruptive effects on H-bonded water.
The attraction of hydrophobic groups is actually caused by the repulsion from the water
What is proton hopping?
Protons jump between water molecules or other polar molecules, this is rapid and reversible meaning proton continually shuttle about inside a cell.
Also called hydrogen ion exchange.
What is the first law of thermodynamics?
Energy cannot be created nor destroyed, only converted between various forms of energy
What is catabolism?
To break down complex molecules into smaller, simpler ones.
Generating both energy and new small molecules which can be used as building blocks for new complex molecules.
What is anabolism?
Biosynthetic pathway that uses energy from catabolism to drive the synthesis of the many larger molecules that form the cell
Define standard free energy change
The standard free energy change of a reaction where one mole of reactant i converted into one mole of product under standard conditions.
(1molar concentration and PH 7)
At equilibrium the rate of the forwards and backwards reaction are equal, True or False?
True
What equation links equilibrium and free energy?
Delta G = -RT lnKeq
What is th equation for Keq?
[Product] / [Reactant]
What effect does Keq have on drug/ligand binding strength?
The larger Keq, the stronger the drug/ligand is bound to the protein
How do coupled reactions work and what’s their importance?
Energetically unfavourable reactions are coupled with energetically favourable reactions - giving an overall -ve delta G and so the process can work spontaneously
How can coupled reaction be used in a linear arrangement? Why is this important in cells?
X —> Y may be unfavourable but Y—>Z may be VERY favourable
Hence the first equilibrium is forced to produce more Y to maintain equilibrium of Y—>Z
This is natures way of ensuring disequilibrium of chemicals in cells.
