CP04 - Bioenergetics and Enzymes - pdf (Spring 2025)

Page 1: Overview of Bioenergetics and Enzymes

Core Subject Areas:
- Chapter 5: The Working Cell
  - Section 5.10: Energy transformations in cells
  - Section 5.11: Chemical reactions and energy release/storage
  - Section 5.12: Role of ATP in cellular work
  - Section 5.13: Enzymes in chemical reactions
  - Section 5.14: Specificity of enzymes
  - Section 5.15: Enzyme regulation by inhibitors
- Chapter 6: Harvesting Chemical Energy
  - Section 6.5: Energy capture from electrons
Prerequisites:
- Understanding of protein structure
- Knowledge of energy principles: energy conservation & transformation
Learning Outcomes:
- Understanding thermodynamics in living systems
- Differentiating between endergonic and exergonic reactions
- Recognizing ATP as energy currency
- Comprehending enzyme functions and regulation
- Identifying electron carriers as energy transporters

Metabolism: All biochemical reactions allowing energy and matter transformation in organisms.
Types of Metabolic Pathways:
- Catabolic Pathways: Release energy by breaking down complex molecules into simpler ones.
- Anabolic Pathways: Use energy to build complex molecules from simpler ones.

Free Energy: Energy available to perform work (beyond random motion).
Chemical Reactions:
- Exergonic Reactions: Release free energy and occur spontaneously.
- Endergonic Reactions: Absorb free energy, requiring coupling with exergonic reactions to occur.

Types of Work in Cells:
- Various functions where free energy is utilized:
  - Mechanical work (movement)
  - Transport work (moving substances)
  - Chemical work (building molecules)

ATP (Adenosine Triphosphate):
- Used in RNA synthesis and as a primary energy carrier.
- Picks up energy from exergonic processes and transfers it to endergonic reactions.
- Universal role in all cell types (eukaryotic and prokaryotic).

Hydrolysis of ATP is exergonic (ATP + H2O → ADP + Pi, ΔG’ = -30.5 kJ/mol).
Requires enzyme ATPases to quickly catalyze the hydrolysis due to high activation energy.

ATP synthesis is an endergonic process, linking exergonic and endergonic reactions.
ATP Cycle: Continuous recycling of ATP through synthesis and hydrolysis.

Enzymes: Catalysts that increase biochemical reaction rates by lowering activation energy.
- Generally, proteins.
- Do not alter the free energy change (ΔG).

Reaction Pathway:
- Substrates (reactants) are converted into products via enzymes without large energy investments.

Enzymes possess specific active sites for substrate binding, critical for catalysis.
Active sites are regenerated after the reaction.

Reaction rates are influenced by enzyme amounts produced and activity regulations.

Substrate Concentration:
- Enzymes have saturation limits.
Temperature and pH:
- These affect the enzyme's performance and structural integrity.

Enzymes can be regulated via inhibitors (decrease activity) or activators (increase activity).
Feedback Inhibition: Product of a pathway inhibits an upstream enzyme.

Terms include:
- Metabolism, Catabolic pathways, Anabolic pathways, Free energy, Exergonic/Endergonic reactions, Enzyme, ATP, Active site, Cohesion, Saturation kinetics, etc.

Questions on topics such as:
- Work versus heat energy transfer
- ATP hydrolysis thermodynamics
- Saturation kinetics explained
- Effects of temperature on enzymatic rates