Biochemistry and Thermodynamics

Overview of Biochemistry and Energy

• Biochemistry focuses on chemical reactions involving living organisms.
• Importance of potential and kinetic energy in biochemical reactions.

Types of Energy

• Potential Energy:

• Stored energy, can lead to change when released.

• Examples:

  • Phosphate bonds in ADP and ATP.
  • Concentration gradients (e.g., across membranes).

• Kinetic Energy:

• Energy of motion, leads to change in biological systems (muscle contractions).

• Conversion between potential and kinetic energy is continuous in cells.

Categories of Biological Energy

• Chemical Energy:

• Energy stored in chemical bonds (e.g., covalent bonds).

• Stronger bonds (covalent) store more potential energy.

• Breaking down polymers into monomers releases energy.

• Thermal Energy:

• Release of heat during chemical reactions.

• Mechanical Energy:

• Energy associated with muscle movement.

Energy Conversion

• Energy transitions from potential to kinetic energy during reactions (e.g., ATP hydrolysis).
• Examples of energy conversion illustrated through organismal behavior (e.g., cat jumping).

Laws of Thermodynamics

• First Law of Thermodynamics:

• Energy cannot be created or destroyed, only converted from one form to another.

• Example: Energy in cat's muscles converts potential energy into kinetic energy when jumping.

• Second Law of Thermodynamics:

• Energy conversions are never 100% efficient; some energy is lost as heat, becoming unavailable for work.

• Example: Heat loss during glucose metabolism prevents energy from being used efficiently in cells.

Entropy and Order

• Entropy refers to disorder in a system, increases in closed systems without energy input.
• Living organisms require constant energy input (from food or sunlight) to maintain order and functionality.

Metabolism

• Metabolism encompasses all chemical reactions in a cell.
• Catabolism: Breakdown of molecules to release energy.
• Anabolism: Synthesis of complex molecules from simpler ones (requires energy).

Chemical Reactions and Energy Changes

• Reactions require energy to change bonding partners.

• Changes in free energy (delta G) indicate if a reaction is energy-releasing (negative delta G) or energy-consuming (positive delta G).

• Key Equations:

• Total Energy = Usable Energy (G) + Unusable Energy (X)

• Change in Free Energy, ΔG = Δ(total energy) - Δ(unusable energy)

• Breaking down glucose releases significant energy (-ΔG).

Conclusion

• Understanding energy dynamics in biological systems is crucial for grasping cellular metabolism and function.
• Future topics: ATP and enzymes elaboration in upcoming lectures.