Overview
This lecture covers inorganic compounds crucial to biochemistry, including water, acids, bases, salts, and their roles in biological systems.
Inorganic vs. Organic Compounds
- Inorganic compounds generally lack carbon-hydrogen bonds; examples include water, acids, bases, and salts.
- Organic compounds contain many carbon-hydrogen bonds, e.g., carbohydrates, lipids, proteins, nucleic acids.
Properties of Water
- Water is vital for life and acts as the body's primary (universal) solvent.
- Hydrophilic solutes (with full or partial charges, e.g., ions, polar molecules) dissolve in water.
- Hydrophobic solutes (nonpolar, no charges, e.g., oils, fats) do not dissolve in water.
- “Like dissolves like”: water dissolves ionic and polar covalent substances but not nonpolar covalent substances.
Acids and Bases
- Acids are hydrogen ion (proton) donors; examples: hydrochloric acid, carbonic acid.
- Bases are hydrogen ion acceptors; examples: sodium hydroxide, sodium bicarbonate.
- When acids or bases ionize in water, they release or accept hydrogen ions.
The pH Scale
- The pH scale (0–14) measures hydrogen ion concentration in a solution.
- Each digit change on the pH scale equals a tenfold change in hydrogen ion concentration.
- Solutions with pH < 7 are acidic; pH > 7 are basic (alkaline); pH = 7 is neutral.
- Normal blood pH ranges from 7.35 to 7.45 (slightly basic).
Buffers and Homeostasis
- Buffers are chemical systems that resist changes in pH, maintaining homeostasis.
- The body regulates pH using chemical buffers, the respiratory system (CO₂ levels), and the renal system (excretion of ions).
Salts and Electrolytes
- Salts dissolve in water to form electrolytes (cations/anions) that conduct electricity.
- Electrolytes are essential for nerve impulse conduction, muscle contraction, and maintaining fluid balance.
Key Terms & Definitions
- Inorganic Compound — lacks carbon-hydrogen bonds.
- Hydrophilic — water-loving; dissolves in water.
- Hydrophobic — water-fearing; does not dissolve in water.
- Acid — donates hydrogen ions (protons).
- Base — accepts hydrogen ions.
- pH — measure of hydrogen ion concentration.
- Buffer — resists pH changes.
- Electrolyte — ion in solution that conducts electricity.
Action Items / Next Steps
- Review types of substances that dissolve in water and why.
- Memorize the normal pH range of blood plasma (7.35–7.45).
- Prepare for questions on acids, bases, buffers, and the role of electrolytes in the human body.