3. CELLS Smallest unit of life that can carry out all the functions of an organism.

4. History of the Cell: 1665 – Robert Hooke discovered and described the fundamental unit of all living things (cells) by using thin slices of cork. He gave the tiny chambers the name “cell” because it reminded him of a monastery's tiny room which were known as cells.

5. History of the Cell: 1674 – Anton Van Leeuwenhoek (“Father of Microbiology”) was the first man to witness a live cell under a microscope. He made many different types of single lens microscopes that could magnify up to 300 X. When observing pond water, he discovered tiny organisms he called "animalcules.”

6. History of the Cell:

7. 1838: Matthias Schleiden (Botanist) concluded that all plants are made out of cells.

8. History of the Cell: 1839: Theodor Schwann (Zoologist) concluded that ALL organisms including animals are made up of cells.

9. History of the Cell: 1855: Rudolph Virchow (Doctor) – proposed that all cells arise from existing cells. –Until 1855: Schleiden and Schwann believed that cells might “crystallize out” from fluids.

10. These discoveries, confirmed by other biologists, are summarized in the CELL THEORY

11. What is the Cell Theory? A fundamental concept in biology that states: 1.Cells are the basic units of life (Hooke) 2.All organisms are made of cells (Schleiden &Schwann) 3.All cells come from existing (other) cells (Virchow)

12. Examples of Cells Amoeba Proteus Plant Stem Red Blood Cell Nerve Cell Bacteria

13. Part of the Microscope

14. Parts of the Microscope A.Occular (eye piece) B.Body Tube C.Revolving Nosepiece D.Objective Lenses E.Stage F.Diaphragm (controls amount of light)

15. G. Light source H. Base I. Fine Adjustment knob J. Coarse Adjustment Knob K. Stage Clips (holds slides) L. Arm Parts of the Microscope

16. Carrying a Microscope

17. Magnification increases the apparent size of a specimen when you view it through the microscope. Calculating Magnification  Magnification of X occular lens magnification objective lens

18. Since microscopes magnify cells we have a new unit of measurement. These new units are called microns. 1mm=1000 µm 1 =1 µm 1000 We can use microscopes to estimate the size of cells we are looking at.

19. a)if the field of view = 1mm then onion cells are ______________ mm or ______________(µm) in length 1mm (1000 µm) Field of view Onion cell 0.5 500 microns Example

20. b)if the field of view = 0.5mm or 500µm then these cheek cells would be mm or ______________ µm in length 0.5 mm (500 µm) Human cheek cell 500 5 100