L. 7 Equilibrium and Thermodynamics

Question 1

L.O.

Answer 1

1. Understand the difference between potential and kinetic energy
2. Explain the concept of equilibrium and how it relates to energy
3. Explain the difference between the thermodynamic and kinetic properties of a reaction.
4. Explain how enzymes act as catalysts, including what effect they have on reaction rates and final concentrations of substrates and products of a reaction.
5. Appreciate how enzymes can be used experimentally (in combination with the labs).
6. Understand that enzymes combine to form enzymatic pathways that are important for living organisms.
7. Describe how a secondary reaction can drive equilibrium and provide energy for an unfavourable interaction.

Question 2

Energy and Entrapy

Answer 2

Energy is the capacity to do work
- Potential Energy
- Kinetic Energy

Bioenergetics:
- The transfer of potential energy to kinetic energy and back in living systems

Entrapy:
- A measure of disorder

Question 3

Laws of Thermodynamics

Answer 3

• Energy can only be transfered, not created or destroyed
• Entrapy of the universe is always increasing

Question 4

Thermodynamics

Answer 4

• The energy something contains

Reactions:
Substrate <=> Product

Product will be favourable if product has lower energy
If energy is higher in the product, it is unfavourable

Question 5

Energy and equilibrium

Answer 5

Weight substitutes for energy
- Heavier = more energy

At equilibrium balance is is maintained, but molecules are constantly interchanging state
-Foward and reverse reactions are happening at the same rate

Question 6

In cells

Answer 6

In living cells reactions never reach true equilibrium
- Increasing concentrations can ‘push’ equilubrium towards the other side

Question 7

Shifting equilibrium

Answer 7

Using up products shifts equilibrium to the right

Question 8

Kinetics

Answer 8

• How quickly we get from one state to another
• May need to go through activation abrrier, breaks bonds before new bonds can be created
• Height of activation barrier usually depicts the time taken and energy required for the reaction.

Question 9

Kinetics Vs thermodynamics

Answer 9

Sugars can be converted into carbon dioxide and water using lots of energy
- But it is very stable, despite it being full of chemical energy

Carbon chemistry is usually under kinetic control
- If left to occur alone, it will be very slow

Question 10

Enzymes

Answer 10

usually end in “ase”
- Enzymes lower the activation energy required for a reaction
- Are biological calalysts
- Most are proteins
- The final equilibrium state and thermodynamics does NOT change

Enzymes stabilise ‘transition’ state, bringing to a lower energy state

Question 11

Enzyme binding

Answer 11

Lock and key model
- Enzymes are specific for their substrates, fit directly in active site

Induced fit model
- The subtrate induces a shape change for optimal substrate binding and activity

Selection model
- Enzyme exists in multiple forms in equilibrium, only one of which will bind, sometimes changing the shape so another enzyme can bind

Question 12

Enzyme characteristics

Answer 12

Enzymes are:
- Biological catalysts
- Mostly proteins
- Highly varied in terms of function, size and ability to be regulated

Question 13

Enzyme regulation

Answer 13

• Individual enzymes evolved to work best at specific temp and pH
• Many require an extra Cofactor for optimal activity
• Can be inhibited on the active site or allosteric site

Question 14

Enzyme pathways

Answer 14

• Enzymes for pathways for metabolism, synthesis of cellular material, communication etc.
• Mutations such as reduced or increased activity/ change/ specificity and regulation cause disease

Question 15

Enzyme locations

Answer 15

• Partly regulated by where they are
• Enzymes in a wrong place can create problems

Question 16

Driving unfavourable interactions by coupling reactions

Answer 16

• Unfavourable interactions need energy input
• Biopolymer formation is intrinsically unfavourable

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