Lecture 13 - Bioenergetics 1 Flashcards
What is Thermodynamics
The flow, transfer, interconversions and transformations of energy
What is the difference between heat and work?
Heat - transfer of energy that changes the motion of the atoms in the surroundings in a chaotic manner
Work - the transfer of energy that changes the motion of the atoms in the surrounding in a uniform manner
What are the 3 most important variables used to describe a system?
Pressure
Volume
Temperature
Relationship between an organism and energy
Organism never at equilibrium with surroundings
Constantly transfers matter and energy with surroundings
Highly ordered
Spontaneous reaction in relation to energy
A reaction that doesn’t require any additional input of energy
What do most chemical reactions result in?
Lower energy
More stable state
Greatest dispersal of motional energy
Enthalpy
The potential energy of a system
Describes changes in:
- Covalent bonds
- Non-covalent bonds
- Motion of atoms due to changes in temperature
It is equivalent to energy transferred by heat in chemical and biological systems
Changes in Enthalpy - Exothermic and Endothermic reactions
Exothermic
- reaction releases energy from the system to surroundings (- delta H)
- energy required to break bonds less than energy released from forming bonds
- enthalpy products < enthalpy reactants
Endothermic
- reactions absorb energy from the surroundings into the system (+ delta H)
- energy required to break bonds greater than the energy released from forming bonds
- enthalpy products > enthalpy reactants
How to calculate Enthalpy
Enthalpy = ms(deltaT) m = mass of reactants s = specific heat of products deltaT = change in temp from reaction Exo reaction deltaH is - Endo reaction deltaH is +
Entropy
Direct measure of disorder of a system
Describes tendency for:
- Motional energy to disperse or spread out
- Matter to disperse or spread out
What does high and low energy mean in relation to entropy?
Low energy means entropy is concentrated
High energy means that it is spread out
Is the entropy of a solution greater than that of a pure solvent or solute?
Yes
Which state has the highest entropy and which has the lowest?
Highest - gas
Lowest - solid
Entropy in Biological Systems
Entropy in living systems is low
Low entropy is thermodynamically allowed due to:
Dispersal of matter
- breakdown of large molecules
Dispersal of energy
- from loss of heat energy from biochemical reactions to surroundings
The constant exchange of energy and matter with an organisms surroundings has two consequences:
- Increase entropy of surroundings and hence the ‘Universe’
2. Allows organism to create order within themselves
