WK3 LEC7: Enzyme & Thermodynamics 낱말 카드

1. Describe different energy types (potential and kinetic energy) and transformations and understand why our

cells need energy

Energy:

- Capacity for work (change)

Potential

- Contained within objects structure/location/chemically

Kinetic

- Actualised energy associated with motion

Thermodynamics

- 1st law, energy is conserved, transferred between forms

- 2nd law: entropy always increases, usable energy is always decreasing

Cellular Needs:

- Biosynthesis: Creation of molecules

- Movement: Contraction

- Active Transport: Moving molecules against gradient

- Thermoregulation: Maintaining temperature

- Signal Transduction: Intra/inter cellular

2. Explain the concept of equilibrium and how it relates to energy.

Equilibrium

- Forward & Reverse reactions are matched

- No macroscopic change, but rxns occur microscopically

- RXN will proceed in a forward/reverse direction to reach equilibrium Gibbs free energy change = 0

Gibbs Free Energy:

- Spontaneous RXNS will always decrease the total free energy available in a system.

ΔG = Gproducts - Greactants

Exogernic (Spontaneous) ΔG < 0

- Thermodynamically favourable

i.e Respiration

Endergernic (Not-spontaneous, requires constant energy supply) ΔG > 0

- Not thermodynamiocally favourable

i.e Photosynthesis, Protein synthesis

3. Explain the difference between the thermodynamic and kinetic properties of a reaction.

Thermodynamics: ΔG

- Determines Spontaneity

- many C-based chemical RXNS which are exogernic occur slowly due to high Ea before reaching transition state, enzymes required

Kinetics: Ea

- Determines RXN speed to reach equilibrium

- Initial energy investment Ea to start RXN

- Lowering Ea decreases time to reach equilibrium (Increases RXN rate)

4. Define what enzymes are and explain their biological function, including what effect they have on reaction

rates and final concentrations of substrates and products of a reaction.

Enzymes:

- Biological catalysts with optimum pH and temperature range

- Lower Ea to increase RXN rate

- Ea lowered by stabilises transition state of reactants (they exist in a lower energy state during intermediate phase)

Biological Function:

- speed up biological reactions, key in metabolism, digestion, synthesis etc

- DO NOT CHANGE ΔG FOR A RXN, CANNOT MAKE AN ENDOGERNIC RXN EXOGERNIC

5. Understand that enzymes combine to form enzymatic pathways that are important for living organisms.

Biological pathways involve countless enzymes in & between to move from reactants to products. (synthesis, metabolism, signalling)

- Many different enzymes contributes to degeneracy/redundancy if one enzyme isn't produced/malfunctions

- alternate pathways can compensate for others

Enzymes Mutations:

- combated by redundancy, but may result in

- reduced/increased activity

- altered substrate specificity

- altered regulation (optimum pH and temperature)

- ultimately disease

Enzymes Location

- enzymes regulated by compartmentalisation, may be found in/outside of cells, or only in specific cell compartments

- activation/deactivation is possible when compartmentalisation cannot be managed

6. Describe how a secondary reaction can drive equilibrium and provide energy for an unfavourable

interaction.

Exogernic Reactions coupled with Endergernic reactions (Use energy from Exogernic catabolism to drive endergernic anabolism)

i.e

Cellular Respiration (Highly exogenic)

Photosynthesis (Highly endogenic

7. Appreciate how enzymes can be used experimentally (in combination with your practical classes).

Control Enzyme Regulation: (Modulating Function to change rate of rxn)

- Conditions: (Temperature, pH, ion balance)

- Cofactor (chemical added for optimal activity)

- Inhibition

Enzyme-Driven RXN rate:

- RXN rate initially linear

- once substrates are used up, plateauing will occur

- doubling enzyme concentration doubles RXN rate (controlling for all other conditions)