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

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