Biology Essentials: Major Cellular Organelles

Introduction

• Cell Complexity: Often oversimplified; actually complex and dynamic.
• Recommended Resource: "Inner Life of the Cell" video from Harvard illustrating cell activity.

Nucleus

• Role: Control center of the cell.
• Functions: Contains genetic blueprints; gene control.

Endoplasmic Reticulum (ER)

• Types:
  • Rough ER:
    • Has ribosomes.
    • Site for protein synthesis.
  • Smooth ER:
    • No ribosomes.
    • Synthesizes lipids.
    • Breaks down toxins.

Ribosomes

• Components: Proteins and ribosomal RNA (rRNA).
• Function: Protein synthesis via translation of messenger RNA.
• Location: Cytoplasm or on the rough ER.

Golgi Apparatus

• Discovered by: Camillo Golgi.
• Function: Modifies, sorts, and packages proteins and lipids for storage or transport out of the cell.
• Analogy: Acts like the "UPS" of the cell.

Lysosomes

• Function: Digestive organelles with enzymes to break down waste.
• Pathway: Enzymes are made in the ER, processed in the Golgi apparatus, and packaged into lysosomes.
• Analogy: "Suicide sac" for digesting obsolete cellular components.

Mitochondria

• Role: Powerhouse of the cell; site of ATP production.
• Structure:
  • Outer membrane.
  • Inner folded membrane (cristae) to increase surface area.
  • Processes: Glycolysis (outside), Krebs Cycle, and Electron Transport Chain (inside).

Vacuoles

• Function: Mainly storage.
• Occurs in: Plant cells.
• Structure: Surrounded by tonoplast membrane.
• Content: Water, pigments, toxins for defense.

Chloroplasts

• Found in: Plant cells.
• Function: Photosynthesis.
• Structure:
  • Thylakoid Membrane: Site of light reactions.
  • Grana: Stacks of thylakoids.
  • Stroma: Liquid interior where Calvin cycle occurs.

Conclusion

• Overviewed major cellular organelles and their functions.
• Highlighted the importance of surface area in organelle structures for maximizing efficiency.