Topic 5 Flashcards
1
Q
Thermos
A
Heat
2
Q
Dynamis
A
Power
3
Q
thermodynamics
A
- study of energy of systems (ie cells, reactions, organisms)
- dictates whether reactions are favourable or not
- all of the chemical and physical reactions that take place in living organisms can be interpreted based on the laws of thermodynamics
4
Q
What is a living organism?
A
- an open system
- exchanges both matter and energy with its surroundings
5
Q
In any physical or chemical change
A
- the total amount of energy in the universe remains constant
- although the form of the energy may change
6
Q
System
A
- a biochemical reaction
- a metabolic pathway
- an individual cell
- an organism
- might convert one form of energy to another
- might lose energy
- when system loses energy, its surroundings gain that energy, so the total energy in the universe in conserved
7
Q
Surroundings
A
- everything else in the universe
8
Q
Universe
A
System + surroundings = universe
9
Q
First law of thermodynamics
A
- conservation of energy
- energy is neither created nor destroyed; only converted from one form to another
10
Q
Heat
A
A manifestation of the kinetic energy associated with the random motion of molecules
11
Q
Potential energy in cells
A
- concentration gradients
- electric potential (charge separation)
- chemical potential energy (bond energy)
- energy from chemical bonds breaking and forming is transformed into energy for work in the cells/body
12
Q
In biological systems, deltaH = deltaE
A
- deltaH is a direct measure of the change of energy, deltaE of a process
- a process that results in an overall decrease in energy of a system (negative deltaH) tends to be favoured
- depends only on the initial and I’d la states of the process - intermediate stages are irrelevant
- the value of deltaH depends on the number and kinds of chemical bonds in the reactants and products
13
Q
Exothermic
A
A chemical reaction gives off heat
- deltaH is negative
14
Q
Endothermic
A
Chemical reaction that absorbs hear
- deltaH is positive
15
Q
Enthalpy (H)
A
- can be measured by a bomb calorimeter
16
Q
Bomb calorimeter
A
Measures the change in temperature of a water jacket surrounding a reaction chamber during a chemical reaction
17
Q
The second law of thermodynamics
A
- systems have a tendency towards randomization (disorder)
- describes energy changes but does not tell us if a reaction is favorable/spontaneous
18
Q
How to predict whether a reaction is favourable?
A
- we must consider both enthalpy plus a second term, entropy, S
19
Q
Entropy
A
- a measure of disorder or randomness, which tens to increase in a spontaneous reaction:
- high disorder = high randomness = high entropy
- the tendency in nature is toward ever greater disorder in the universe - the total entropy is continually increasing
20
Q
Ice melting entropy
A
- process requires an input of energy (heat so deltaH is positive) but it happens spontaneously at room temperature
- molecules go from a more ordered state in ice to a less ordered state in water
- makes the overall reaction thermodynamically favourable
21
Q
Hydrophobic effect is a consequence of entropy
A
- nonpolar molecules spontaneously aggregate in an aqueous solution, increasing their order, (deltaS < 0, is negative)
- however the water molecules that were ordered around the non-polar molecules are no released, increasing their disorder (deltaS»_space; 0, is positive)
- net deltaS for the system is positive, drives the aggregation of the non-polar (hydrophobic) molecules
- process is energetically favourable
22
Q
Protein folding is an entropy-driven process due to the hydrophobic effect
A
- an unfolded protein is disordered and therefore high in entropy whereas a folded protein is more ordered and lower in entropy
- however, in the unfolded protein hydrophobic regions are exposed to polar water molecules
- the water molecules must order themselves around the hydrophobic regions of the protein to maximize their hydrogen bonding - the organized water is low in entropy
- protein folding increase the order of the protein which is entropically unfavourable but it releases the ordered water molecules, which is entropically favourable - the net deltaS is positive
- protein folding also optimizes weak interactions which is enthalpically favourable
23
Q
What results in a net entropy increase in the universe?
A
- a chemical reaction may result in a decrease in entropy of the system
- the entropy of the surroundings may increase due to the release of heat
