Cell Theory (History and Development of Cell theory

• Cell Theory


  The development and refinement of magnifying lenses and light microscopes made observation and description of microscopic organisms and living cells possible
• Hans and Zacharias Janssen invented the first compound microscope


  1590
• Compound microscope


  Two lenses put together in a tube
• Robert Hooke discovered and came up with the name "cells" while looking through a microscope at a piece of cork


  1665
• Theodore Schwann viewed animal tissues under a microscope and observed that animal tissues are made of cells


  1839
• Cell Theory (Schwann)


  • All organisms are composed of one or more cells
  • The cell is the structural unit of life
• Rudolph Virchow


  developed the third tenet of the cell theory: "All cells come from pre-existing cells"
• Three main principles of Cell Theory

  • All living organisms are made up of cells
  • Cells are the most basic unit of life
  • All cells arise from pre-existing cells
• Compound light microscope


  Uses glass lenses like the early microscopes Robert Hooke used
• Modern compound light microscope


  Uses electricity, a source of light, and can magnify images up to 1000x without blurring
• Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM)


  Can magnify specimens up to 500,000x
• Anton van Leeuwenhoek

  1683 observed some of the first living cells under a simple microscope and named them "animalcules"
• Robert Brown discovered the nucleus in the plant cells of an orchid


  1833
• Matthias Jakob Schleiden a German botanist, concluded that all plant tissues are composed of cells