Lecture Notes: Specialized Cells

Introduction to Specialized Cells

• Definition: A specialized cell has a structure suited to its function.
• Misconception: It's not a super cell but a cell with a specific role.
• Importance: Differentiation leads to cells with varied structures and functions.

Plant Cells

General Specialization

• Cells have different structures based on function.
• Example: Leaf cross-section shows diverse specialized cells.

Epidermal Cells

• Function: Form a protective boundary, help retain water.
• Types:
  • Upper and lower epidermis
  • Waxy cuticle layer can be one or several cells thick based on environment.
  • Generally lack chloroplasts.

Guard Cells

• Specialized epidermal cells controlling stomata.
• Role: Regulate gas exchange and prevent water loss.

Trichomes

• Hair-shaped epidermal cells.
• Functions:
  • Protection through secretion of toxins.
  • Reflect light in hot environments.
• Example: Sundew plant uses trichomes to digest insects.

Mesophyll Cells

• Palisade Mesophyll:
  • Rich in chloroplasts for photosynthesis.
• Spongy Mesophyll:
  • Loosely packed, irregular shapes aid in gas exchange.

Vascular Tissues

• Xylem and Phloem:
  • Specialized for transporting water and photosynthetic products.

Animal Cells

Red Blood Cells (RBCs)

• Function: Carry oxygen using hemoglobin.
• Structure: Disc shape for maximum surface area.
• Unique Feature: Mature cells lack nucleus and organelles.

White Blood Cells

• Types: Various types with different functions like granulocytes.
• Function: Immune response, engulfing pathogens.

Muscle Cells

• Energy: High mitochondria content for ATP.
• Types:
  • Smooth Muscle: Spindle shapes.
  • Skeletal Muscle: Long, cylindrical, multi-nucleated.
  • Cardiac Muscle: Branched, have intercalated discs for synchronized contraction.

Neurons

• Function: Sense stimuli and transmit signals.
• Structure:
  • Dendrites receive impulses.
  • Axons transmit impulses.
• Interesting Fact: Can be over a meter long.

Conclusion

• Specialized cells form specialized tissues.
• Further exploration in biological levels of organization.

Closing

• Encouragement to stay curious and explore more about biology.