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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.