Lecture Notes: Organic Macromolecules - Proteins

Introduction

• Organic macromolecules: carbon hydrogen-based, large molecules.
• Focus on proteins; nucleic acids to be covered in the next session.
• Proteins are crucial molecules in the body, directed by the DNA to form.

Key Points to Remember

1. Structure
2. Examples
3. Functions

Protein Structure

• Monomer: Amino Acid
  • Central carbon atom.
  • Four covalent bonds:
    • Amino Group: Nitrogen bonded to two hydrogens.
    • Hydrogen Atom.
    • Carboxyl Group: Carbon double-bonded to oxygen and bonded to hydroxyl (OH) group.
    • R Group (Variable Group): Different for each amino acid; determines the amino acid's properties.
  • 20 different amino acids.
• Importance of Structure
  • Structure determines function; compared to key-lock mechanism.
  • Complex 3D structures critical for function.

Levels of Protein Structure

1. Primary Structure

   • Linear chain of amino acids linked by peptide bonds.
   • Greater than 100 amino acids in length.

2. Secondary Structure

   • Alpha Helix: Coil/spring shape.
   • Beta Pleated Sheet: Folded accordion-like.
   • Involves hydrogen bonding within molecule backbone.

3. Tertiary Structure

   • Interactions among R groups and with the environment.
   • Hydrogen bonds, disulfide bonds involved.
   • Environment factors (temperature, pH) influence folding.

4. Quaternary Structure

   • Complex of multiple subunits.
   • Can be Globular (e.g., hemoglobin) or Fibrous (e.g., collagen).

Examples of Proteins

• Enzymes: Catalyze all chemical reactions in the body.
• Antibodies: Defense against pathogens.
• Collagen and Keratin: Structural proteins for strength and protection.
• Hemoglobin: Transports oxygen in red blood cells.
• Communication Proteins: Neurotransmitters, hormones, cell membrane receptors.

Functions of Proteins

• Catalysis of reactions, regulation of bodily processes.
• Structural support in tissues.
• Transport of molecules.
• Communication within and between cells.
• Energy source (less optimal, involves breaking down body structure).

Conclusion

• Proteins are vital for numerous functions in the body.
• Next video will cover nucleic acids.

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Take care of yourselves and each other.