Thermodynamics Flashcards
Metabolism
All of the chemical reactions occurring in a living organism
Thermodynamics
thermos = heat/energy, dynamics = movement
Energy
is defined as the ability to do work.
All objects have energy.
kinetic - motion
potential - “stored” due to their location or chemical structur
1st law of thermodynamics
Energy can be converted from one form to another, but cannot be created or destroyed.
example: Exothermic and Endothermic Reactions
During a chemical reaction, existing chemical bonds must be broken, and new bonds are formed in the products.
-this change determines the amount type of reaction that occurs
Activation Energy
The amount of energy needed to break the bonds of the reactants is called the activation energy.
Exothermic Reactions
If the amount of energy needed to break the bonds of the reactants is less than the amount of energy released when the products form, then the reaction is said to be exothermic. It releases energy into the surroundings.
(exo = out of. Energy comes out of the chemicals and into the surroundings)
2nd Law of thermodynamic
Each time energy is transferred/moved around, some of it is “lost” - it can no longer be used or stored.
This lost energy is usually released as heat
Entropy
Entropy measures the randomness or disorder of the universe.
The heat LOST during a change increases entropy, since the energy is now less organized.
Entropy also increases when there are more product molecules than reactant molecules - the products are more disordered or random than the reactants.
Reaction Spontaneity
In general, it is “easier” to become more disordered, so reactions that increase entropy are said to be spontaneous and thermodynamically favourable.
Since living things are very organized, they are constantly fighting against entropy. And the only way to do this is to continue to add energy to them. Therefore, energy-requiring reactions are non-spontaneous and thermodynamically unfavourable.
Exergonic Reaction
During an exergonic reaction, free energy increases - energy goes out of the system, and can be used to power some other process.
The change in energy, called 𝝙G, is negative
The products have less stored energy than the reactants had originally
Endergonic Reaction
During an endergonic reaction, free energy decreases - energy is absorbed by the system, and must be provided by some other process.
In this case 𝝙G is positive
The products have more stored energy than the reactants originally had
Reaction Comparison
Exergonic 𝝙G ＜ 0
Spontaneous
Increases entropy
Releases free energy - allows cells to do something!
Endergonic 𝝙G ＞ 0
Non-spontaneous
Decreases entropy
Requires free energy - the cell must provide energy to allow the reaction to occur
Anabolism
Building-up reactions that take smaller, simpler molecules and combine them to make larger, more complex molecules.
Be endergonic
Be non-spontaneous
Have 𝝙G > 0
Energy is STORED in the new bonds of the more complex product molecules. The products contain more energy than the reactants.
Together, the two reactions combined are exergonic, and so are energetically favourable.
Catabolism
Breaking-down reactions that take larger, more complex molecules and break them apart into smaller, simpler molecules.
Be exergonic
Be spontaneous
Have 𝝙G < 0
Energy is RELEASED as the less complex product molecules are formed. The products contain less energy than the reactants.
Together, the two reactions combined are exergonic, and so are energetically favourable.
