1. CONTRIBUTIONS TO THE CELL THEORY
Timeline of scientists and their discoveries

2. 1) Anton von Leeuwenhoek
1600’s
Dutch businessman
Invented 1st simple light microscope

3. Anton von Leeuwenhoek (con’t)
Observed tiny organisms in pond water
Organisms were nicknamed “wee beasties”

4. 2) ROBERT HOOKE 1665 English physicist
Observed flowers, insects, and plant tissue

5. ROBERT HOOKE (con’t) Observed thin slices of cork (oak tree)
Coined the term “cell” based on the rooms in a monastary

6. 3) ROBERT BROWN
1833
Observed plant cells under the microscope

7. ROBERT BROWN (con’t)
Observed a dark structure inside each cell and coined the term “nucleus”

8. 4) MATTHIAS SCHLEIDEN
1838
German botanist: scientist who studies plants
Concluded all plants are made up of cells

9. 5) THEODORE SCHWANN 1839 German biologist
Concluded all animals are made of cells

10. 6) RUDOLF VIRCHOW 1855 German Physician Studied cell reproduction
Concluded all cells arise from preexisting cells

11. The cell theory 1. All living things are composed of cells
2. Cells are the basic unit of structure and function in living things.
3. All cells arise from preexisting cells.

12. Introduction to Cells
Chapter 6

13. Levels of Organization
All living organisms can be studied on many levels
From smallest to largest they are:
Chemical (atoms & molecules)
Cells
Tissues
Organs
Organ Systems
Whole Organism

14. Basic Structure of Cells
All cells have a cell membrane and cytoplasm
Cell Membrane: thin, flexible barrier around cell
Composed of lipids and proteins
Cytoplasm: jelly-like material inside the cell
All cells contain organelles
Organelles: small structures that perform different functions within a cell

15. Prokaryotic Cells Do NOT have a nucleus
Instead a small ring of DNA is free-floating in center of cell
Organelles do NOT have a membrane
i.e.: bacteria (very simple organisms)

17. Eukaryotic Cells Contain a nucleus Organelles are membrane-bound
Much more complex
i.e.: plants, animals, fungi