1. Discovery and study of cells Unit 2 part1 Packet 4 Unit 2 part1 Packet 4

2. Robert Hooke (1665) Examined cork under a simple microscope…described what he saw as “little rooms” (cellulae, Latin) Cell biology pioneers Anton van Leeuwenhoek (1674) Also used rudimentary microscope to examine many things…blood, pond water, scrapings of plaque from teeth. Described what he saw as animicules…the first descriptions of bacteria and protists.

3. Light Microscopes

4. Magnification vs. Resolution  Magnification - increase in size  Resolution - measure of clarity  Magnification - increase in size  Resolution - measure of clarity

5. Electron Microscopes  Use a beam of electrons instead of light  SEM and TEM  Use a beam of electrons instead of light  SEM and TEM

6. Transmission Electron Microscope (TEM): for studying the internal structure of cells Spinach Cell Chloroplast

7. Scanning Electron Microscope (SEM): for studying the surfaces of cells Cells are covered in metal, then reflect electrons.

8. SEM

9. A View of the Cell We’ve come a long way since the time of Hooke (1665) thanks to more sophisticated microscopes. By the mid-1800s there was an established cell theory.

10. Cell Theory  Cells are the basic unit of organization of living things  Every living organism is made of one or more cells  All cells come from other cells already in existence

11. Types of cells  Two major categories:  Prokaryotic  Eukaryotic  Two subcategories:  Plant  Animal  Organisms made of eukaryotic cells can be unicellular or multicellular  Two major categories:  Prokaryotic  Eukaryotic  Two subcategories:  Plant  Animal  Organisms made of eukaryotic cells can be unicellular or multicellular