Lecture Notes: Organelles and Compartmentalization

Overview

• Introduction to organelles and compartmentalization.
• Distinction between prokaryotic and eukaryotic cells.
• Importance of understanding cellular structures for research.

Types of Cells

Prokaryotic Cells

• Lack membrane-bound organelles.

Eukaryotic Cells

• Contain membrane-bound organelles (e.g., mitochondria, nucleus).

Key Differences

• Eukaryotic Cells: Have organelles separated by membranes.
• Prokaryotic Cells: No membrane-bound organelles.

Compartmentalization

• Definition: Division of cells into different regions/enclosed spaces (organelles) by one or more membranes.
• Prokaryotic cells lack this ability.

Organelles

• Membrane-bound subcellular structures performing specialized functions.
• Important organelles include:
  • Mitochondria: ATP production.
  • Nucleus: Stores DNA.
  • Lysosomes: Break down waste materials.

Important Terms

• Compartmentalization: Formation of distinct regions in a cell, each with specific functions.
• Organelles: Membrane-bound structures within eukaryotic cells.

Non-Organelle Components

• Cytoplasm: Not an organelle; refers to everything within the plasma membrane excluding the nucleus.
• Cytoskeleton: Not membrane-bound; provides cell structure but is not an organelle.
• Cell Wall: Only found in plant cells; outside the plasma membrane, hence not classified as an organelle.

Importance of Compartmentalization

1. Danger Management:

   • Lysosomes contain hydrolytic enzymes that can be destructive if not contained.
   • Prevents enzymes from damaging the cell's own components.

2. Vesicle Formation / Endocytosis:

   • Allows uptake of substances (like viruses) while isolating them from the cytoplasm.
   • Helps in transporting beneficial molecules without interference.

3. Enhanced Cell Efficiency:

   • Analogy of a school with compartments (classrooms) to illustrate organization and efficiency.
   • Prevents interference between cellular processes and allows for specialized environments.

Example of Efficiency

• Transcription and Translation:
  • Transcription occurs in the nucleus; translation occurs in the cytoplasm.
  • Compartmentalization allows these processes to happen sequentially without interference.

Tools for Research

1. Microscopes

• Used to magnify and observe cells and structures.
• Types: Light microscope, electron microscope.

2. Centrifugation

• Spins samples to separate components based on size and density.
• Heavier components settle at the bottom.

3. Chromatography

• Separates substances based on solubility in a solvent.
• More soluble substances travel further up the medium.

4. Gel Electrophoresis

• Separates DNA/nucleic acids based on charge.
• DNA fragments migrate through a gel towards a positive electrode; different lengths separate differently.

Summary of Key Points

• Eukaryotic cells are organized into compartments by organelles, while prokaryotic cells are not.
• Compartmentalization is crucial for cellular efficiency, safety, and organization.
• Several tools and techniques are used in research to study cells and organelles.