Life Requires A Continual Energy Flux Flashcards
Life is not a thing, but a
Process powered by energy harvested from the environment
The total entropy of a system and it’s surroundings
Increases for a spontaneous process
Entropy
A measure of the disorder or randomness of a system
What is the fate of the universe in line With the 2nd law
- heat death
- the big chill
- all matter has reached an equilibrium state of maximum disorder
- no spontaneous reactions
- no energy available
Heat energy always flows from
Hot to cold
Heat
The random motion of atoms or molecules in collision
How do steam engines use the second law?
- heat generates water vapour
- vapour expansion coupled to mechanical work
The second law dictates that
Processes proceed spontaneously until an equilibrium is reached
What is statistical mechanics?
- predicts how atomic or molecular properties (mass, charge, position) determine physical properties of matter
- probability distributions of relationship between micro system states and macroscopic matter properties (eg temperature, viscosity)
Who developed statistical mechanics?
- Ludwig Boltzmann
- James Clerk Maxwell
- Josiah Willard Gibbs
Entropy equation
S = k.ln W
S = entropy
k = constant
W = number of possible micro states corresponding to the macro state of the system
Why will a system almost always be found either in the state of maximum disorder or moving towards it?
There are so many more possible disordered states than owhat der d ones
What is the second law, under the lens of statistical mechanics?
Statistical probability for matter made or mechanically colliding particles
Life clearly involves
An increase in order (decrease in entropy)
Local entropy can decrease spontaneously (matter becomes more ordered) as long as
The total entropy of the system as a whole increases
Life is possible because
It’s biochemical processes increase the entropy of the environment
Living organisms take up
- ordered forms of energy (low entropy) from the environment
- release them as less ordered forms (high entropy)
Entropy within a cell
- is decreased (highly ordered macromolecules are formed)
- total energy of the system + surroundings increases
Macromolecule formation does not occur
Spontaneously
How is macromolecule formation achieved?
- expenditure of free energy by nucleotide triphosphate hydrolysis (eg ATP or GTP)
Spontaneity equation
ΔSsystem + ΔSsurroundings = ΔSuniverse = +ve
Gibbs free energy concept
ΔG is always negative for a spontaneous process
ΔG equation
ΔG = ΔHsystem - TΔSsystem
H
Enthalpy
T
Temperature in Kelvin
Enthalpy
Measure if change in heat in the system (reaction)
For spontaneous reactions, ΔHsystem is
Negative
Spontaneous reactions are
Exothermic
What does exo/endothermy depend on
The chemical bond energies of the reactants and products
Why do covalent bonds form?
They are more stable arrangements that separate atoms
Breaking chemical bonds takes
Energy
The more stable (strong) the bond
The more energy it takes to break it
ΔHsystem
- net energy release
- energy added to break reactant bonds - energy released from forming product bonds
In exothermic reactions,
- more energy is released from forming the product bonds than is required to break the reactant bonds
- ΔHsystem < 0
A reaction can be made to occur spontaneously by
Coupling to a second, more favourable reaction
Example of reaction coupling for spontaneity
Glucose + fructose -> sucrose + H2O (+27kJ/mol)
ATP + H2O -> ADP + Pi (-30kJ/mol)
Glucose + fructose + ATP -> sucrose + ADP + Pi (-3kJ/mol)
The chemistry of life is kept away from equilibrium by
Expenditure of energy
Stable, non-equilibrium systems
- When energy is poured into a system and the system dissipates, that energy slides towards increased entropy
- on this slide, it can become poised in an orderly configuration
Is ATP a universal energy currency
Yes
What is a nucleoside?
Base + sugar (no phosphate)
Energy can be captured as ATP by
- Catabolism of organic molecules coupled to ATP and NADH synthesis
Heterotroph
Ah organism that depends on intake of organic environmental carbon sources
Photoautotrophs
convert light energy to chemical energy using inorganic molecules such as H2O or H2S as electron donor
How do autotrophs fix carbon into sugars
- extracted electrons generate ATP and reduced electron carriers (eg NADPH)
- these drive biochemical cycles for atmospheric CO2 fixation
Non-equilibrium systems are
An inevitable consequence of the second law in a system that is abundant in energy
Evolution of photosynthesis allows
Translocation of life away from hydrothermal smokers
Heat and CO2 escape causes
Tertiary energy loss
