Lecture 2: Chemistry of Life

Review of Previous Lecture

• Discussed matter and energy
• Atoms and bond formation
• Types of reactions (making and breaking bonds)
• Molecules formed from multiple bonds
  • Two categories: inorganic and organic
  • Inorganic molecules lack hydrocarbons
• Introduction to water properties

Water Properties

• Water is a polar molecule
  • Electronegativity difference between oxygen and hydrogen
  • Partial negative charge on oxygen, partial positive on hydrogen
  • Polarity leads to surface tension and ability to dissolve substances
• Hydration of ions (e.g., Na⁺ and Cl⁻ in solution)

Inorganic Chemistry

• Discussed ions and electrolytes
  • Electrolytes carry electrical charges in solution
  • Common electrolytes: sodium, potassium, calcium, and chloride
  • Importance in body fluid balance and health
• Acids and Bases
  • pH scale: measure of hydrogen ion concentration
  • Neutral pH is 7 (equal H⁺ and OH⁻ concentrations)
  • Acidic (pH < 7) and basic (pH > 7)
  • Blood pH: tightly regulated between 7.35-7.45

Buffers

• Buffer systems resist changes in pH
• Important for maintaining physiological pH
• Examples: bicarbonate buffer system in blood

Introduction to Organic Chemistry

• Organic molecules contain hydrocarbons
• Four classes: carbohydrates, lipids, proteins, nucleic acids
• Function as polymers and monomers

Carbohydrates

• Hydrated carbon molecules
• Types: monosaccharides, disaccharides, polysaccharides
  • Monosaccharides: single sugar units (e.g., glucose)
  • Disaccharides: two sugars linked (e.g., sucrose)
  • Polysaccharides: long chains for storage (e.g., glycogen in animals)

Lipids

• Hydrophobic molecules (fats, oils, waxes)
• Types include fatty acids, glycerides, phospholipids, steroids
  • Fatty acids: saturated and unsaturated forms
  • Triglycerides: storage form of fats
  • Phospholipids: critical for cell membranes
• Importance of fatty acid saturation
  • Saturated fats: solid at room temperature, tightly packed
  • Unsaturated fats: liquid at room temperature, less tightly packed

Additional Notes

• Trans fats and their health implications
• Impact of lipid structure on packing and health

Conclusion

• Next lecture will discuss proteins
• Continued focus on chemical foundations for understanding body systems