1. The Cell Theory A Timeline

2. Late 1500’s Late 1500’s Hans and Zacharias Janssen
Dutch lens grinders, father and son
produced first compound microscope (2 lenses)

3. 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”

4. Anton von Leeuwenhoek (1674)
Looked at pond water organisms
First to see living microscopic organisms.
Made careful sketches.

5. Matthias Schleiden -- 1838 German Botanist (studied plants)
Viewed plant parts under a microscope
Discovered that plant parts are made of cells
He concluded:
“All plants are made of cells.”

6. Theodore Schwann -- 1839 “All animals are made of cells.”
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 one or more cells.
The cell is the basic unit of life in all living things.
New cells are produced from existing cells.

9. Cell Similarities
Cells come in many shapes and sizes with different duties but …
All are surrounded with a cell membrane
All cells have hereditary material (DNA)
All have cytoplasm and organelles. Cytoplasm is the fluid within a cell which provides a safe environment for the organelles. Organelles are the structures within the cell that have specific duties to make the cell a functioning unit.

10. Two Types of Cells Eukaryotic Are complex and of different types.
Have a nucleus and many organelles.
Contain more DNA due to different jobs within the cell. DNA is linear (in a line).
Possess a cell membrane or a cell wall.
All living things other than bacteria.

12. Two Types of Cells Prokaryotic Contain no nucleus.
Have no membrane covered organelles, but do have ribosomes to make protein.
Possess circular DNA.
Are bacteria.