Lecture on Organelles and Compartmentalization

Introduction

• Focus on core curriculum from B2.2
• Definition: Organelles are structures within a cell specialized for specific functions.
• Detailed study in A2.2 (Cell Structure).

Organelles

• Structures with specific functions within a cell (e.g., mitochondria, rough ER).
• Not all important cell structures are organelles (e.g., cell wall, cytoskeleton, cytoplasm).
• Common misconception: Organelles are not exclusive to eukaryotes.
  • Prokaryotes do have some organelles but lack membrane-bound organelles.

Types of Organelles

• Non-Membrane Bound: Prokaryotes and Eukaryotes

  • Examples: Ribosomes, Centrioles, Microtubules

• Single Membrane-Bound: Eukaryotes

  • Examples: Golgi apparatus, Lysosomes, Vacuoles, Vesicles, Smooth and Rough ER

• Double Membrane-Bound: Eukaryotes

  • Examples: Nucleus, Mitochondria, Chloroplasts

Compartmentalization in Eukaryotes

• Eukaryotes are compartmentalized with membrane-bound organelles.
• Advantages:
  • Protection and Processing:
    • Nucleus protects DNA and aids in mRNA editing.
  • Enzyme Concentration:
    • Mitochondria can concentrate enzymes due to compartmentalization.
  • Environmental Control:
    • Maintain specific pH, solute concentrations within compartments.
  • Storage of Dangerous Substances:
    • Lysosomes store destructive enzymes safely.

Key Associations

• Membrane-bound organelles = Eukaryotic cells.
• Prokaryotic compartmentalization limited to cell membrane separating inner and outer environments.
• Compartmentalization with organelles = Exclusive to Eukaryotes.

Conclusion

• Understanding the role and types of organelles is crucial.
• Compartmentalization offers functional advantages in eukaryotic cells.