Metabolic Processes - Intro to Thermodynamics Flashcards
Metabolism
The sum of all of the chemical reactions in a cell or organism
Catabolic reactions
Larger molecules are broken into their subunits
Anabolic reactions
Larger molecules are built up from their subunits
Work
Performed when energy is used to move and object against an opposing force (e.g. friction or gravity)
Energy
The capacity to do work
Potential energy
The stored energy that an object possesses as a result of its position relative to other objects or its chemical structure (energy of what can be)
Kinetic energy
The energy of motion
Chemical potential energy
- Stored in electrons and protons
- During chemical reactions, chemical potential energy can be released or absorbed
The first law of thermodynamics
The total energy in a closed system is constant. Energy cannot be created or destroyed; it can only be converted from one form to another (law of energy conservation)
Bonds during chemical reactions
- Breaking bonds requires an input of energy (electrons must be pulled away from nucleus)
- When new bonds form, energy is released (electrons lose their potential energy as they get closer to nucleus)
Activation energy
The amount of energy needed to break the bonds of the reactants (must be supplied)
Exothermic reactions
Amount of activation energy < energy released (releases energy intro surroundings)
Endothermic reactions
Amount of activation energy > energy released (absorbs energy from surroundings)
The second law of thermodynamics
In every energy transfer or conversion, some of the useful energy in the system becomes unusable (cannot be used to do work) and increases the entropy of the universe (usually in the form of thermal energy)
Entropy
- Measures the randomness or disorder of the universe
- Heat lost during a change increases entropy since the energy is now less organized
- Entropy increases when there are more product molecules than reactant molecules (products are more disordered than reactants)
Reaction spontaneity
It is easier to become more disordered so reactions that increase entropy are spontaneous and thermodynamically favourable (living things are very organized so they are constantly fighting against entropy by adding energy to reactions - non-spontaneous reactions)
Gibbs Free Energy
- Energy that is free to do work
- Represented by G
- Delta G represents the change in free energy between reactions and products
Exergonic reactions
- Free energy decreases (goes out of system)
- Change in energy is negative
- Products have less stored energy than reactants had originally
- Spontaneous
- Increase entropy
- Release energy
Endergonic reactions
- Free energy increases (energy absorbed by system and must be provided by other process)
- Change in energy is positive
- Products have more stored energy than reactants had originally
- Non-spontaneous
- Decrease entropy
- Require energy input
