1. Levels of Organization
• Atom
• Molecule
• Organelles
• Cells
• Tissue
• Organ
• Organ System
• Organism

2. The Cell Theory – a timeline
• Late 1500’s: -first lenses used in Europe
-used to determine cloth
quality (weave and precision)
-combos of lenses gave better
view
• Early 1600’s: Leeuwenhoek uses
microscope to study nature

3. Early 1600’s
• Leeuwenhoek
• Used a hand made
microscope to look
at pond water
• First to see living
microscopic
organisms
• Made careful
sketches
Early 1600’s

4. Robert Hooke ( 1665)
• Used light
microscope to look
at thin slices of plant
tissues -- cork
• Looked empty, like
monk’s chamber
• Called tiny chambers
“cells”

5. Matthias Schleiden 1838
• German Botanist
(plants)
• All plants looked at
were made of cells,
so concluded:
“All plants are
made of
cells.”

6. Theodore Schwann -- 1839
• German scientist
who studied animals
-- zoologist
• Saw that all animals
he studied were
cellular so
concluded:
“All animals are
made of cells.”

7. Rudolf Virchow -- 1855
• German physician
who studied cell
reproduction
• “Where a
cell exists,
there must
have been a
preexisting
cell…..”

8. The Cell Theory
• All living things are composed of
cells
• Cells are the basic units of structure
and function in living things
• New cells are produced from existing
cells

9. Prokaryotes vs. Eukaryotes
• Prokaryotes: *NO NUCLEUS
*Small and Simple – few
organelles
*Have cell membranes
and cytoplasm
Ex. Bacteria
• Eukaryotes: *Contain nuclei
*Contains organelles that
perform specialized functions
*Uni-or multicellular

10. Prokaryotes vs. Eukaryotes
• Prokaryotes: *NO NUCLEUS
*Small and Simple – few
organelles
*Have cell membranes
and cytoplasm
Ex. Bacteria
• Eukaryotes: *Contain nuclei
*Contains organelles that
perform specialized functions
*Uni-or multicellular