Transcript Development of Cell Theory

Development of Cell Theory
By
Diana L. Duckworth
Rustburg High School
Campbell County
Key Actors (must know)
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Van Leeuwenhoek
Hooke
Brown
Schleiden
Schwann
Virchow
Pasteur
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
Robert Hooke 1655
• Observed cells in cork
• Actually just cell walls
• Coined the word “cell”
http://www.clt.astate.edu/mhuss/toppage6.htm
Robert Brown 1833
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookCELL2.html
• Discovery of Nucleus
• An opaque spot in
cells of epidermis of
orchids
• Soon observed in
other cells
• Brownian motion –
random motion of
particles
Schleiden
Schwann
http://kentsimmons.uwinnipeg.ca/cm1504/celltheory.htm
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
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
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
http://kentsimmons.uwinnipeg.ca/cm1504/celltheory.htm
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