Lecture Notes: Biochemistry and the Role of Water

Introduction to Biochemistry

• Biochemistry focuses on the chemical makeup and reactions in living organisms.
• Two types of chemicals:
  • Inorganic Compounds: Typically do not contain carbon.
  • Organic Compounds: Contain carbon as a central atom.
• Importance of these compounds in biological systems.

Inorganic Compounds

1. Water

   • Essential molecule for life on Earth.
   • Living organisms are 70-95% water.
   • Water's chemistry: Polar covalent bonds create partial charges, leading to polarity.
   • Hydrogen bonding allows water molecules to loosely associate.

2. Properties of Water Essential for Life

   • Cohesion:

     • Water molecules attach to each other (hydrogen bonds).
     • Responsible for phenomena like water transport in plants and surface tension.
     • Examples: Water striders walking on water, capillary action in plants.

   • Temperature Moderation:

     • Absorbs/releases heat with minimal temperature change.
     • Specific Heat: High, requiring significant energy to change temperature.
     • Facilitates climate moderation (e.g., coastal areas).
     • Evaporative Cooling: Helps organisms maintain temperature (e.g., sweating).

   • Expansion Upon Freezing:

     • Ice is less dense than water, allowing it to float.
     • Importance to aquatic life in cold climates.

   • Universal Solvent:

     • Dissolves many substances due to polarity.
     • Hydration shells surround solutes, aiding dissolution.
     • Differentiates between Hydrophilic (water-loving) and Hydrophobic (water-fearing) substances.

Organic Compounds

• Not covered in detail in this lecture but will focus on:
  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic Acids

Additional Notes

• Temperature and heat concepts:
  • Heat: Total kinetic energy.
  • Temperature measures heat (Celsius).
• Solutions in water can be made as percent or molar solutions.
• Hydrophobic vs. Hydrophilic:
  • Hydrophobic substances like oil do not mix well with water.
  • Colloids are stable suspensions of particles.

Conclusion

• Water's unique properties due to its chemistry are crucial for sustaining life and maintaining ecological and biological balance.