1. Development of Cell Theory By Diana L. Duckworth Rustburg High School Campbell County

2. Key Actors (must know) • Van Leeuwenhoek • Hooke • Brown • Schleiden • Schwann • Virchow • Pasteur

3. Compound Microscope • Jansen (Holland) 1595 • (more than one lens) • Anton van Leeuwenhoek • Single lens monocular in 1660’s • Observed bacteria & protozoa • Continued publishing for 50 years • After his death, no good microscopes for century http://www.clt.astate.edu/mhuss/toppage6.htm

4. Robert Hooke 1655 • Observed cells in cork • Actually just cell walls • Coined the word “cell” http://www.clt.astate.edu/mhuss/toppage6.htm

5. Robert Brown 1833 • Discovery of Nucleus • An opaque spot in cells of epidermis of orchids • Soon observed in other cells • Brownian motion – random motion of particles http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookCELL2.html

6. Schleiden Schwann http://kentsimmons.uwinnipeg.ca/cm1504/celltheory.htm

7. Cell Theory – First Statement • Schleiden & Schwann – separately stated • “All living things are composed of living cells.” 1838 -1839 • Schleiden – detailed observation of nucleus • Gave credit to Brown about nucleus(but not Schwann about cell theory) • Most important part of cell • All other parts develop from nucleus • Still believed that cells arose spontaneously

8. Rudolph Virchow • 1855 – “Omnis cellula e cellula” • All living cells arise from pre-existing cells • No spontaneous generation http://kentsimmons.uwinnipeg.ca/cm1504/celltheory.htm

9. Louis Pasteur • Experimentally disproved spontaneous generation • Florence flask – open allowed bacteria to settle into sterile medium • S-neck flask with cotton plug – no bacteria • Remove S-neck got bacteria http://kentsimmons.uwinnipeg.ca/cm1504/celltheory.htm

10. http://kentsimmons.uwinnipeg.ca/cm1504/celltheory.htm

11. Cell Theory – Main Tenents • All life forms are made of one or more cells • Cells only arise from pre-existing cells • The cell is the smallest form of life • 1880 – Weissman • Cells living today can trace their ancestry back to ancient times – there must be a common ancestral cell