Chemistry of Life Lecture Notes

Introduction

• Overview of the chapter on chemistry in Anatomy and Physiology.
• The chapter covers essential chemistry concepts necessary for understanding anatomy and physiology.
• Topics covered include:
  • Chemical elements
  • Structure of atoms
  • Molecules and compounds
  • Chemical bonds
  • Nonpolar vs. polar covalent bonds
  • Properties of water
  • Chemical reactions
  • Inorganic vs. organic compounds

Chemical Elements

• All matter is composed of chemical elements.
• Elements are recognized by their symbols (e.g., O for oxygen).
• 96% of body mass is made of four elements: Oxygen, Carbon, Hydrogen, Nitrogen.
• Lesser elements make up 3.6% (Calcium, Phosphorus, etc.).
• Trace elements (0.4%) include iodine, zinc, etc.

Structure of Atoms

• Atoms: smallest units of an element retaining properties.
• Composed of protons (+), neutrons (neutral), and electrons (-).
• Nucleus contains protons and neutrons.
• Electrons exist in electron clouds surrounding the nucleus.
• Electron shells determine the number of electrons (1st shell: 2, 2nd: 8, 3rd: 18).

Ions and Isotopes

• Isotopes: Atoms with the same number of protons but different neutrons.
• Ions: Atoms that gain or lose electrons.
  • Anion: Negative ion (gains electrons)
  • Cation: Positive ion (loses electrons)

Molecules and Compounds

• Molecules: Two or more atoms bonded together.
• Compounds: Molecules containing at least two different elements.

Chemical Bonds

• Types of bonds:
  • Van der Waals forces: Weak attractions.
  • Hydrogen bonds: Weak attraction between hydrogen and electronegative atoms.
  • Ionic bonds: Attraction between anions and cations.
  • Covalent bonds: Sharing of electrons; strongest bonds.
• Covalent bonds can be nonpolar (equal sharing) or polar (unequal sharing).

Properties of Water

• Water is a universal solvent, cohesive, adhesive, chemically reactive, and has thermal stability.
• Essential for chemical reactions in the body.

Chemical Reactions

• Metabolism: Sum of all chemical reactions in the body.
  • Catabolism: Breakdown of molecules (e.g., decomposition reactions).
  • Anabolism: Building up molecules (e.g., synthesis reactions).
• Types of reactions:
  • Decomposition: Large molecules into smaller ones (hydrolysis).
  • Synthesis: Small molecules into larger ones (dehydration synthesis).
  • Exchange reactions: Atoms or groups exchanged (double displacement).
  • Reversible reactions: Can proceed in either direction.

Inorganic vs. Organic Compounds

• Inorganic compounds: Typically lack carbon, simple structures (e.g., water, salts).
• Organic compounds: Always contain carbon, complex structures.

Four Categories of Carbon Compounds

1. Carbohydrates
   • Include sugars, glycogen, starches.
   • Types: Monosaccharides, disaccharides, polysaccharides.
   • Main function: Energy source.
2. Lipids
   • Hydrophobic molecules (e.g., fatty acids, triglycerides).
   • Function: Energy storage, insulation, structure of cell membranes.
3. Proteins
   • Polymers of amino acids.
   • Functions: Structure, communication, transport, enzymes, immunity, movement.
4. Nucleotides and Nucleic Acids
   • Include ATP, DNA, RNA.
   • Functions: Genetic information storage and transfer.

Conclusion

• Understanding the chemistry of life is essential for comprehending anatomy and physiology.
• Further videos available for deeper understanding of DNA and RNA.