Cell Theory

• Cell Theory


  The fundamental concept in biology that describes the basic unit of life. It provides insights into the structure, function, and origin of living organisms.
• The Postulates of Cell Theory

  • All living things are composed of one or more cells
  • The basic unit of life is the cell
  • All cells arise from pre-existing cells
• Hans and Zacharias Janssen invented the first so-called compound microscope


  1590s
• Robert Hooke observed cork cells using a compound microscope and described the microscopic structures as "Cellulae" (Latin: small rooms)


  1665
• Antonie Van Leeuwenhoek first observed single-celled microorganisms, which he called "animalcules"


  1674
• Robert Brown observed a structure within plant cells that he termed the "nucleus" (from the Latin word for "kernel")


  1831
• Felix Dujardin described the gelatinous fluid in protozoans as "sarcode", later recognized as protoplasm or cytoplasm


  1835
• Jan Evangelista Purkinje coined the term "protoplasm" to describe the contents of a cell


  1839
• Matthias Jacob Schleiden proposed that the cell is the basic unit of structure in plants


  1838
• Theodor Schwann proposed that the cell is the basic unit of structure in animals


  1839
• Matthias Schleiden and Theodor Schwann co-founded the cell theory, proposing the three main postulates in 1839
• Rudolph Virchow stated the principle of "omnis cellula e cellula" (all cells arise from pre-existing cells)


  1855
• The Three Postulates of Cell Theory


  • All living things are composed of one or more cells
  • The basic unit of life is the cell
  • All cells arise from pre-existing cells
• The Modern Version of the Cell Theory

  • Energy flow occurs within cells
  • Heredity information (DNA) is passed on from cell to cell
  • All cells have the same basic chemical composition
• Louis Pasteur discovered that heat kills germs in liquids, preventing bacterial growth, food spoilage and foodborne illnesses


  1862
• Walther Flemming made meticulous observations of cell division, particularly his detailed studies of chromosomal behavior during mitosis


  1882
• Ernst Ruska invented the first electron microscope using several lenses in a series


  1931
• The Development of the Cell Theory

  • 1590: Compound microscope invented
  • 1665: Robert Hooke observed cork cells
  • 1674: Antonie Van Leeuwenhoek observed single-celled microorganisms
  • 1839: Theodor Schwann and Matthias Schleiden co-founded the cell theory
  • 1855: Rudolph Virchow stated the principle of "omnis cellula e cellula"