1. Science Foundations An introduction to cells, cell theory and a variety of microscopes used in science.

2. Objectives 1.Define cell 2.Outline the discoveries that led to the development of the cell theory 3.Compare the operation of a compound light microscope with that of an electron microscope 4.State the cell theory 5.Identify a limiting factor on the size of cells 6.Describe the relationship between cell shape and cell function 7.Distinguish between prokaryotes and eukaryotes

3. Cells are the smallest unit of matter that can carry on all the processes of life They are the basic units of living organisms

4. Without technology we were limited to studying macroscopic (big) objects

5. We didn’t know about cells until the 1600’s Why didn’t we study them earlier? Their discovery and our ability to study them depended on the development of the MICROSCOPE!

6. The Discovery of Cells Robert Hooke (1665) –Looked at dead cork cells with a primitive microscope –Saw “little boxes”

7. These “little boxes” reminded him of the small rooms in which monks lived in at monastery, which were called cells This is how cells got their name

8. Anton van Leeuwenhooek (“Lay-von-hook”) Looked at living cells under the microscope

10. The Cell Theory Three German Scientists: Schleiden, Schwann & Virchow 1.All living things are made up of cells 2.Cells are the basic units of structure and function in an organism 3.Cells only come from the reproduction of existing cells

11. Simple Light Microscope Like the one Leeuwenhooek used Contains one lens Uses light to view objects

12. Modern Compound Light Microscope Uses two or more lenses to magnify the image

13. light microscopes allowed us to study microscopic objects

14. Images from a compound light microscope

15. Electron microscopes have allowed us to study even smaller objects or to see even more detail in large objects Electron Microscopes

16. Scanning Electron Microscope (SEM) used to scan the surfaces of cells gives a 3-dimensional image

17. Micrographs from an SEM

18. A fruit fly as seen with the unaided eye

19. SEM micrograph of a fruit fly at 60X

20. A micrograph from an SEM showing bacteria on the point of a pin

21. Transmission Electron Microscope (TEM) used to study the structures contained within a cell

22. Micrograph from a TEM

23. color enhanced micrograph from a TEM

24. Iodine atoms Scanning Tunneling Microscope (STM) uses the flow of electrons to create computer images of atoms

25. Cells contain specialized structures called organelles (“tiny organs”) Most organelles are surrounded by a membrane = membrane-bound organelles

26. Cells can be divided into two large categories based on the organelles they contain

27. Cells that have no membrane-bound organelles are called Prokaryotes

28. Cells that do contain membrane-bound organelles are called eukaryotes