1. The Cell Theory
Hairy T-cell

2. Definition = Three part theory about cells
1. All living things are made of cells.

3. Part 2 of the Theory
2. The cell is the basic structural and functional unit of life.

4. Part 3 of the Theory 3. All cells come from pre-existing cells.
yeast cells dividing

5. Who came up with this theory?
All plants are made of cells!
1. Schleiden (circa 1838)
Onion skin cells

6. Who came up with this theory?
All animals are made of cells!
2. Schwann
Human red blood cells

7. Who came up with this theory?
3. Virchow
All cells come from pre-existing cells!

8. How big are cells? Microscopic (mostly) Measured in microns µm
(micrometers).
A µm is one millionth of a meter =
10-9 m = one thousandth of 1 mm.

9. How big are cells? Smallest free-living cell = Mycoplasma genitalium
Size = 0.2 to 0.3 µm

10. How big are cells? Bacteria e.g. Eschericia coli (aka E.coli)
Size=1 µm by 3 µm

11. How big are cells?
Human red blood cell = 8 µm in diameter

12. How big are cells? Largest cell on the human body = ovum Size=
1000 µm in diameter
(1 mm)

13. How big are cells?
Smallest cell in the human body =
sperm cell.

14. How big are cells? Largest cell with a metabolism = Chaos chaos
Size=1-5 mm in length.
common name =
Giant Amoeba
Chaos diffluens, is an amoeba closely related to the giant amoebae

15. How big are cells?
Largest cell = yolk of an ostrich egg

16. Ostrich, egg, humans

17. Ostrich emerged from egg

18. How can we study cells? Problem: They are microscopic! Solution:
Use a microscope!

19. Types of Microscopes Compound light microscope
Light passes through lenses to magnify image up to 1000X
Can observe living cells

20. Types of Microscopes 2. Electron microscope
Uses a beam of electrons to magnify image
> 1000X
Kills cells being observed

21. Common features of all cells
Small size – allows materials to move via diffusion
Diffusion = process by which molecules move from levels of high concentration to levels of low concentration until equilibrium is reached

22. Diffusion
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23. Common features of all cells
1. Cell Membrane – selectively/differentially permeable (lets some things in and out)

24. Common features of all cells
2. Cytoplasm – semi-fluid material in which cell organelles float

25. Common features of all cells
3. Nucleic acid containing genetic code :
Which nucleic acid?
DNA

26. Common features of all cells
4. Cytoskeleton – proteins that support the cell
(Microtubules &
microfilaments)

27. Common features of all cells
5. Ribosomes
– make proteins

28. If Cells could be really big ……
Star Trek - The Immunity Syndrome

29. Bibliography http://www.hotlinecancer.com/?cat=28

30. Bibliography http://www.pacpress.com/level3/micron.htm
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