Lecture Notes: Organelles Part Two

Ribosomes

• Function: Major site of protein synthesis.
• Process: Translation of mRNA to proteins primarily occurs in ribosomes.
• Types of Ribosomes:
  • Bound Ribosomes: Found in the rough endoplasmic reticulum (RER).
  • Free Ribosomes: Located in the cytoplasm.

Endoplasmic Reticulum (ER)

• Types of ER:
  1. Rough Endoplasmic Reticulum (RER)
     • Studded with ribosomes.
     • Main Function: Protein synthesis via embedded ribosomes.
     • Also involved in synthesizing membranes.
  2. Smooth Endoplasmic Reticulum (Smooth ER)
     • Lacks ribosomes.
     • Main Functions:
       • Lipid Synthesis: Major site for lipid production.
       • Carbohydrate Breakdown: Converts carbohydrates into simpler forms.
       • Processing Chemicals: Plays a role in detoxification, especially in liver cells.
         • Example: Breaks down drugs and waste products.

Golgi Apparatus

• Function: Processes and ships products made by the cell.
• Structure:
  • Cis-phase: Receives products via vesicles.
  • Cisternae: Folded areas where processing/modification occurs.
  • Trans-phase: Ships processed products to their destinations using vesicles.
• Products Processed:
  • Proteins from the rough ER.
  • Main Destinations for Processed Products:
    • Lysosomes
    • Plasma Membrane
    • Outside the Cell

Lysosomes

• Function: Digestion and disposal of waste.
• Mechanism: Fuses with structures to digest or eliminate waste.
• Roles:
  • Breakdown of damaged organelles.
  • Digestion of food.
  • Neutralization of foreign bodies (e.g., viruses).

Mitochondria

• Function:
  • Known as the "powerhouse of the cell" for producing ATP.
  • Role in apoptosis (programmed cell death).
  • Involved in detoxification (not all cells) and signaling (cell-to-cell communication).

Conclusion

• Discussion: Questions can be posted in the discussion board.
• Important Note: Review all parts of the lesson for a comprehensive understanding.