Eukaryotic Cells

Introduction to Eukaryotic Cells
  • Eukaryotic cells differ from prokaryotic cells in complexity and size.
  • Feature internal membranes, compartmentalization, and specialized organelles.
Learning Outcomes
  • Identify major structures in animal and plant cells.
  • Understand the functions of each structure in a eukaryotic cell.
  • Describe the endomembrane system and the journey of proteins within the cell.
Eukaryotic Cell Overview
  • Complexity: Much larger than prokaryotic cells, with distinct organelles.
  • Factory Analogy: Compares cellular functions (e.g. nutrient import, protein export) to those of a factory.
Major Structures in Animal Cells
  • Nucleus: Encloses genetic material; contains nucleolus for ribosome production.
  • Endoplasmic Reticulum (ER):
    • Rough ER: Studded with ribosomes; synthesizes proteins and membranes.
    • Smooth ER: Synthesizes lipids; detoxifies drugs and stores calcium.
  • Golgi Apparatus: Modifies, sorts, and ships proteins; acts as a processing center.
  • Lysosomes: Digestive organelles that hydrolyze macromolecules.
  • Mitochondria: Powerhouse of the cell; generates ATP through cellular respiration.
  • Cytoskeleton: Provides structure and facilitates movement; consists of microtubules and filaments.
Major Structures in Plant Cells
  • Similar to animal cells but with additional structures:
  • Cell Wall: Provides rigidity and protection; made of cellulose.
  • Chloroplasts: Site of photosynthesis; converts sunlight into chemical energy.
  • Central Vacuole: Storage function; important for plant cell growth and maintenance.
Nucleic Acids
  • Types:
    • DNA (Deoxyribonucleic Acid): Stable; contains instructions for protein synthesis.
    • RNA (Ribonucleic Acid): Less stable; functions in the process of translating DNA instructions into proteins.
  • Nucleic acids are polymers of nucleotides, essential for storing and transmitting genetic information.
The Endomembrane System
  • Components: Nuclear envelope, ER, Golgi apparatus, lysosomes, vacuoles.
  • Functions: Regulates protein traffic and performs metabolic functions, interconnected via vesicles.
    • Protein Synthesis Journey:
    1. Ribosome synthesizes proteins.
    2. Proteins enter Rough ER for folding and modification.
    3. Transported to the Golgi for further processing.
    4. Packaged into vesicles for delivery to the plasma membrane or lysosomes.
Cytoskeleton
  • Structure:
    • Composed of microtubules, microfilaments, and intermediate filaments.
  • Functions:
    • Provides structural support, facilitates intracellular movement, and aids in cell motility (flagella, cilia).
Cell Junctions and ECM
  • Intercellular Junctions:
    • Tight Junctions: Prevent leakage of fluids.
    • Desmosomes: Anchor cells in place.
    • Gap Junctions: Allow for communication between cells.
  • Extracellular Matrix (ECM): Composed of proteins such as collagen; vital for cell communication and structural integrity.
Conclusion
  • Understanding the complexity and interactivity of eukaryotic cells is crucial for studying various biological processes. Each organelle plays a distinct role in maintaining cellular functions and homeostasis.