Topic 2 - Thermodynamics - Biology 241 - University of Calgary

• Biochemical Reactions
• Cells
• Organisms
• Ecosystems

What can systems be? (4)

• No exchange of energy or matter with surroundings.

Isolated System

• Exchanges energy with surroundings.

Closed System

• Exchanges energy and matter with surroundings.

Open System

C) Open

Biological systems are...

A) Isolated
B) Closed
C) Open

• Must absorb needed and remove unneeded molecules.

Why are biological systems open systems?

• The ability to cause change.

Energy

• Change that requires energy.

Work

Any of these answers are correct:
• DNA Replication
• Protein Synthesis
• Metabolism
• Mobility
• Reproduction
• Transport
• Cell Division

List three types of work that cells/organisms perform.

• Stored energy of an object due to its position or chemical structure.

Potential Energy

• Energy of motion or change.

Kinetic Energy

B) High Potential Energy

A molecule with lots of non-polar covalent bonds has...

A) Low Potential Energy
B) High Potential Energy

• The arrangement of electrons in its bonds.

What changes the potential energy within a molecule?

• Energy is neither created nor destroyed.

The First Law of Thermodynamics

• Changes location or changes forms.

What happens to the energy within a system according to the first law of thermodynamics? (2)

• Sum of potential energy and kinetic energy of a system.

Enthalpy

Yes, due to the energy change in the system.

Does the enthalpy change when work occurs?

• Delta H (∆H)

What is the symbol for change in enthalpy?

• Exothermic

If heat is released, the ∆H is...

• Endothermic

If heat is absorbed, the ∆H is...

• Products have less enthalpy than reactants.
• Heat released to surroundings.

What are the two characteristics of an exothermic reaction?

• Products have more enthalpy than the reactants.
• System absorbs heat from surroundings.

What are the two characteristics of an endothermic reaction?

• A reaction that is able to occur under current conditions.

Spontaneous

Yes.

Is an ice cube to liquid water a spontaneous reaction?

No, since it requires sunlight to begin the process.

Is photosynthesis a spontaneous reaction?

• Instantaneous

Spontaneous reactions are not...

• Nonspontaneous

If a reaction is spontaneous, then it is ___________________ in the reversed direction.

• A reaction that cannot occur under the current conditions.

Nonspontaneous

No.

Is liquid water to an ice cube a spontaneous reaction?

Yes.

Can exothermic and endothermic reactions both be spontaneous?

• How dispersed the energy of the system and surroundings is.

Entropy

• Delta S (∆S)

What is the symbol for change in entropy?

• Positive

If energy has higher dispersion, then ∆S is...

• Negative

If energy has a lower dispersion, then ∆S is...

• The total entropy of the universe if always increasing.

The Second Law of Thermodynamics

• Spontaneous

Entropy determines if a reaction is...

• ∆Stotal = ∆Ssystem + ∆Ssurroundings

What is the equation for total entropy?

• Measure of energy in a system that is free to do work.

Free Energy

• The amount of energy that was used to make the change.

The change in free energy in a reaction is measured as...

• More

For work to occur, energy must be available to carry out the change and reactants must have ______ free energy than the products.

• Delta G (∆G)

What is the symbol for free energy?

• Positive

If energy is available, the change in free energy is...

• Negative

If energy is not available, the change in free energy is...

• Negative free energy.
• Spontaneous.

What are the characteristics of exergonic reactions? (2)

• ∆G = -T∆Stotal

What is the equation that relates free energy to the total entropy of a system and its surroundings?

• Positive free energy change.
• Nonspontaneous.

What are the characteristics of an endergonic reaction? (2)

• Enough energy available to change the system and the total entropy of the universe increases.

What causes exergonic reactions?

• Not enough energy to change the system, total entropy of the universe decreases.

What causes endergonic reactions?

∆G = ∆H - T∆Ssystem

What is the equation that relates free energy, entropy, and enthalpy?

• Exergonic

Are biological reactions exergonic or endergonic?

• The rate of the forward reaction = the rate of the reverse reaction.

Chemical Equilibrium

• The reverse reaction is spontaneous.

What does a positive tabulated standard free energy mean?

∆G = ∆G° + RT(ln(product/reactant))

What is the equation that involves standard free energy?

• Chemical reactions in the cells that change food into energy.

Metabolism

• Breaking down of complex molecules.

Catabolism

• Amino acids

If a protein undergoes catabolism, what is the product?

• Building up of complex molecules.

Anabolism

• Protein

If an amino acid undergoes anabolism, what is the product?

• A series of connected reactions.

Biochemical Pathways

• Biochemical Pathways

In cells, metabolic reactions are linked to...

• Endergonic

Is anabolism endergonic or exergonic?

• False, it is exergonic.

Catabolism is endergonic, true or false?

• When the second reaction contains the first reactions product as a substrate.

Connected Reactions

• Nitrogenous Base (Adenine)
• Ribose (Sugar)

What is adenosine made up of?

• Potential Energy

What type of energy does ATP store?

• Negative compressed charges.

Where does the potential energy in ATP come from?

• Reaction of the interaction of chemicals with water, leading to their decomposition.

Hydrolysis

• A single reaction with two things happening, which occur at the same time and same place.

Coupled Reactions

• Coupled

What is the first reaction of glycolysis considered?

• No, since it only has one thing occurring.

Is the second reaction of glycolysis considered coupled?

• Yes.

Is the third reaction of glycolysis a coupled reaction?