ALL LECTURES Flashcards
Define system?
System: a part of the universe in which we are interested in
Open system?
On which can exchange both matter and energy with its environment
Isolated system?
one which can only exchange energy
Closed system?
one which cannot exchange either matter or energy with its surroundings
Define the first law of thermodynamics?
energy cannot be lost only transferred
Define the second law of thermodynamics?
if the energy of both the system and its surroundings increases, it results in a spontaneous reaction
Equation to describe the second law of thermodynamics.
Delta G (universe)>0=Delta g (surroundings) + Delta g (system)
Define entropy?
measure of disorder
When does delta g apply?
constant temperature, and pressure
Equation for delta g?
Delta g= deltaH-TDeltaS
Value of delta g at equilibrium? (2marks mention 2 things)
- Delta G =0
2. min
Maxima values of the derivate of delta g vs minima (in terms of the systems stability)
Maxima= unstable as a small change to the conditions of a system will change the equilibrium drastically, will spontaneously move towards equilibrium. Minima= stable = equilibrium (small change in conditions will not change the position of equilibrium)
What Is proportional to free energy of a reaction
m0les
Endergonic reaction?
position of equilibrium is towards the reactants. Occurs spontaneously in the reverse direction. DeltaG>0
Exergonic reaction?
- One in which occurs spontaneously in the forward direction
- DeltaG<0
What does delta G not account for? Why?
Activation energy
that is to do with kinetics
Two factors effecting Delta G?
Coupled
concentrations
Equation which relates free energy and concentration?
Delta G= RTLog(keq)
keq= mass action ratio
Mass action ratio
concentration of products/ “ reactants to the power of their moles
Standard delta G equation? And what are the conditions for this to be apply?
Delta G= -RTln(keq)
k=298 p=100kpa 1 molar concentrations ph=7
Relationship between delta G and Keq?
a) Delta g<0 …. Keq ……..
b) Delta G=O
c) Delta g>0
a) keq>1
b) keq=1
c) keq<1
Standard conditions?
298 kelvin
100 kpa
1 molar concentrations
pH=7
How do coupled reactions work? (2marks)
couple a exergonic and endergonic reaction together in which there overall DeltaG Is negative and therefore the reaction is feesable
ATP?
standard intermediary of energy within cells
Example of a metabolic reaction involving ATP which requires coupling?
formation of glucose-6-phophate
using hexokinase enzyme
ATP> ADP +Pi
Glucose +pi> glucose-6-phosphate
Cycle in which uses coupled reactions. An example of a coupled reaction within it?
citric acid cycle citrate formation Pyruvate> acetyle CoA and acetyl CoA+ Oxalocactate> citrate citrate synthase
What properties of ATP make it such a great energy currency?(3 marks)
- High energy phosphate bonds
which have negative Gibbs free energies, therefore easily hydrolysed - steric clashes between phosphate bonds
- resonance hybrids of single phosphates are stable (therefore prefer to be alone/ hydrolyse)
Kinetic stability of ATP? Therefore what is required to aid phosphate transfer, why is this useful?
Kinetically stable therefore an enzyme required. Enables cells to have control over the hydrolysis of ATP etc
What type of enzyme is usually used during these ATP hydrolysis.
Kinase
Phosphate transfer potentials?
Gibbs free energy in which the transfer of a phosphate to another biological molecule has.
