Cells - Structure and Function

Important Events in the Discovery of Cells

The Cell Theory of Biology

Properties of Cells

Cells are complex and highly organized

Cells contain a genetic blueprint and machinery to use it

Cells arise from the division of other cells

Cells acquire and utilize energy

Cells can perform a variety of chemical reactions

Cells can engage in mechanical activities

Cells can regulate activities

Cells all contain the following structures:

Types of Cells

  • Pro = before; karyon = nucleus
  • relatively small - 5 to 10 um
  • lack membrane-bound organelles
  • earliest cell type


  • Originally thought to be prokaryotes
  • relatively small - 5 to 10 um
  • lack membrane-bound organelles
  • Usually live in extreme environments (thermophiles, halophiles, etc)


  • Eu = true; karyon = nucleus
  • contain membrane-bound organelles
  • Evolved from prokaryotes by endosymbiotic association of two or more prokaryotes
  • Include Protists, Fungi, Animals, and Plants


Features of Prokaryotic Cells

  • Capsule - outer sticky protective layer
  • Cell Wall - rigid structure which helps the bacterium maintain its shape
    • this is in NO way the same as the cell wall of a plant cell
  • Plasma membrane - separates the cell from the environment
  • Mesosome - infolding of plasma membrane to aid in compartmentalization
  • Nucleoid - region where nakedDNA is found
  • Cytoplasm
    • semi-fluid cell interior
    • no membrane-bound organelles
    • location for metabolic enzymes
    • location of ribosomes for protein synthesis


Properties of Eukaryotic Cells


Images of Vesicle Transport Between Endomembrane Organelles  

Endosymbiotic Origin of Chloroplasts and Mitochondria