Topic 2: Thermodynamics Flashcards
What is an Isolated system?
It does not exchange matter or energy with its surrounding
What is a Closed system?
It exchanges energy with its surroundings
What is an Open system?
It exchanges both energy and matter with its surroundings
What kind of system is a biological system?
An Open system
- Acquiring energy and matter from their surroundings
- Remove unneeded waste molecules
What is Energy?
The ability to cause change
What is Work?
The change that requires energy, for work to occur, energy must be available to carry out the change
Examples of work cells/organisms do?
- Synthesis of biomolecules
- Transport of molecules
- Cell division
- Motility
What is the First Law of Thermodynamics?
Energy is neither created nor destroyed
- Can change location and forms
Where must all energy that enters a system come from?
The surroundings
What is Potential Energy?
Stored energy due to position
What is Kinetic Energy?
Energy of motion/change
What kind of energy do electrons have?
Both Potential and Kinetic energy
What happens as electrons move closer to the atomic nucleus?
Potential energy is converted to light and heat
Electrons further from the atomic nucleus have more?
Potential energy
Potential energy within a molecule depends on?
- Arrangement of electrons in their chemical bonds
- Increased non-polar covalent bonds = more PE
What is a chemical gradient?
A high concentration of solute on the membrane’s side (PE) is converted into KE as the solute moves down its concentration gradient.
What is Enthalpy?
- The sum of PE and KE in the system
- Variable is H
When work occurs what happens to the system?
Its enthalpy and entropy changes
What is the change in enthalpy?
Measured as the amount of heat that is released to, or absorbed from the surroundings
If heat is released, Enthalpy is?
Negative
If heat is absorbed, Enthalpy is?
Positive
What does exothermic mean?
Products have less enthalpy than the reactants, energy is released
e.g.
Glucose + ATP —> Glucose-6-P + ADP
Enthalpy: -35kJ/mol
What does endothermic mean?
Products have more enthalpy than the reactants
e.g.
Glucose-6-P —> Fructose-6-P
Enthalpy: +12 kJ/mol
What is a spontaneous reaction?
- A reaction that can happen under the current set of conditions
- NOT instantaneous
If a reaction is spontaneous then under the same conditions…
It is non-spontaneous in the opposite direction
What does non-spontaneous mean?
A reaction that can not occur under the current condition
What are important in “Current Conditions”?
- Temperature
- pH
- Concentration of product and reactants
- Pressure (salinity)
Does enthalpy determine if a reaction is spontaneous?
No
What is Entropy?
- How dispersed or spread out the energy of the system and surrounding is
- The variable for it is S
If energy has become more dispersed…
Entropy is positive
If energy has become less dispersed…
Entropy is negative
What is the Second Law of Thermodynamics?
- The total entropy of the universe is always increasing
- Every transfer or transformation of energy must increase the total entropy of the universe
What determines spontaneity?
Entropy, when it is a positive value it is spontaneous, when it is a negative value it is non-spontaneous
The total entropy change is?
Total entropy = entropy of the system + entropy of the surroundings
- Entropy of the system can decrease if the entropy of the surroundings increases to a greater degree
What is free energy?
- A measurement of the energy in the system that is free (available) to do work
- The variable is G
In a spontaneous reaction, what should the free energy look like in reactants and products?
More free energy in reactants than in products
When Free Energy (G) is negative
Energy is available
When Free Energy (G) is positive
Energy is not available
What is an Exergonic Reaction?
Free energy is released, products have less free energy than reactants, and the reaction proceeds spontaneously.
What is an Endergonic Reaction?
Free energy is gained, products have more free energy than reactants, and the reaction is not spontaneous
What is the relationship between change in free energy and total entropy?
Change in free energy = - (temperature)(total entropy)
What is Chemical Equilibrium?
Occurs when the rates of forward and reverse reactions are equal
What happens as a spontaneous reaction proceeds?
The condition changes, the concentration of reactants decreases and the concentration of products increases
How do you make a reaction proceed further if there is not enough free energy in the system to allow further overall change?
- Add more reactants
- Decrease amount of products
What is Metabolism?
The sum of all reactions in a cell
What is Catabolism?
The breaking down of complex molecules (releases energy)
What is Anabolism?
The building up of complex molecules (uses energy)
What are metabolic reactions linked to?
Biochemical (metabolic) pathways
What are connected reactions?
If the product of the first reaction is the substrate for the second reaction
e.g
glucose —> glucose-6-P
glucose-6-P —> fructose-6-P
All real reactions are?
Exergonic
How is ATP converted into ADP?
ATP hydrolysis:
1 phosphate group is broken off and bonds with HOH
What is a coupled reaction?
2 reactions that occur at the same time and the same place
e.g. Production of glucose-6-P
1. Glucose becomes phosphorylated
2. ATP is hydrolyzed (reacts with water)
(Curvy arrows used for ATP, NADH, and FADH2 which are frequently used in biochemical reactions)
What are the first two reactions of Glycolysis?
- The first reaction of glycolysis is a coupled reaction
- The first reaction is connected to the second reaction
- The second reaction of glycolysis is not coupled to the second reaction
glucose —> glucose-6-P —> fructose-6-P
ATP ~> ADP
