Notes on Animal Cells

Key Features of Animal Cells

  • Shape: Not regular; can change shape (e.g., phagocytes can engulf materials).
  • Vacuoles: Smaller than plant cell vacuoles; involved in exocytosis and endocytosis.
  • Ribosomes: Animal cells have 80S ribosomes; can be free or on rough endoplasmic reticulum (ER).

Organelles and Structures

  • Nucleus: Contains the nucleolus (ribosome synthesis).
  • Rough Endoplasmic Reticulum (RER): Site of protein synthesis, membrane synthesis.
  • Smooth Endoplasmic Reticulum (SER): Involved in lipid and carbohydrate metabolism; detoxification and hormone synthesis.
  • Golgi Apparatus: Modifies, packages, and 'tags' proteins for transport.
  • Lysosomes: Small sacs that contain enzymes for digestion and waste disposal; formed from the Golgi apparatus.
  • Centrioles: Microtubule structures involved in nuclear division; absent in higher plants.
  • Mitochondria: Double-membrane organelle; produces ATP, number depends on energy needs.

Comparisons with Plant Cells

  • Vacuoles:
    • Plant Cells: Large, for water storage.
    • Animal Cells: Small, mainly for transport.
  • Centrioles: Present in animal cells, absent in plant cells.