1. The History Behind Cells
Cell Theory
The History Behind Cells

2. Where does life come from?

3. Spontaneous Generation
Spontaneous Generation: The idea that life can appear from the non-living environment
Francesco Redi disproved this idea through his meat experiments

4. Spontaneous Generation
Louis Pasteur’s Experiment

5. Microscope Invented Hans & Zacharias Janssen
Made 1st compound microscope (2 lenses)
Allowed people to see things never before seen!

6. Robert Hooke 1655 Used microscope to look at oak cork
He observed “tiny little boxes”
Called structures “cells”

7. Review Who named cells because they looked like “tiny boxes”?
Francesco Redi
Louis Pasteur
Robert Hooke
Albert Einstein

8. Anton Van Leeuwenhoek 1675 Used a simple microscope (1 lens):
Observed blood, rainwater, sperm etc.
Called them “animalcules” because they looked like little animals

9. Matthias Schleiden 1838 German botanist
Discovered that plants are also made of cells!

10. Theodor Schwann 1850 German zoologist
Viewed animal parts under microscope
Discovered animals were made of cells

11. Rudolph Virchow 1858 German Doctor
Concluded that all living cells come only from other living cells

12. Review
Who was the first person to observe living cells? (He called them animalcules)
Robert Hooke
Francesco Redi
Anton van Leeuwenhoek
Rudolph Virchow

13. Cell Theory The Cell Theory:
The work of many scientists led to the development of the Cell Theory!
The Cell Theory:
1) All living things are made from one or more cells
2) Cells are the basic unit of structure and function in living things
3) All cells come only from other living cells

14. Review Which is NOT part of the cell theory?
All living things are made of 1 or more cells
Cells come from non-living things
Cells come only from other living cells
Cells are the basic unit of structure and function

15. Cool Jobs In Science
Molecular Biology

16. The Microscope

17. Why is it Important?
The microscope allowed scientist to observe things that could not be seen with the naked eye
Cells for example!
Makes things appear larger than they really are!

18. How does it Work? Microscopes use glass lenses to bend light
This makes things appear larger or smaller depending on the shape of the lens
Compound microscopes: have more than one lens!
This means they can magnify things even more!

19. Comparing Powers of Magnification
We can see better details with higher the powers of magnification, but we cannot see as much of the image.
Which of these images would be viewed at a higher power of magnification?

20. What’s my power?
To calculate the power of magnification, multiply the power of the eyepeice by the power of the objective.
What are the powers of magnification for each of the objectives we have on our microscopes?

21. Calculating Magnification
To find the total magnification of a compound microscope you must multiply the magnifying power of both lenses!
Example: Lens 1 = 10X magnification
Lens 2 = 50X magnification
Total magnification = 10 X 50 = 500X

22. Practice
Ocular Lens is 10x & Objective lens is 7x Total Magnification?
10 X 7 = 70x
Ocular Lens is 4x & Objective lens is 10x Total Magnification?
4 X 10 = 40x

23. Electron Microscopes
Today scientists can use electron microscopes to look inside cells!
These microscopes use electrons instead of light to magnify object even more!
Same particles that light up your television!

24. Parts of a Microscope

25. Function of Parts Body Tube: separates eyepiece from objective lens
Eyepiece: contains lens that magnifies 10X
Nosepiece: holds objectives lenses and allows rotation

26. Function of Parts Objective lens (High Power): Magnifies 40X
Objective lens (Low Power): Magnifies 10X
Coarse Adjustment Knob: moves body tube to focus with low-power objective lens
Fine Adjustment Knob: moves body tube to focus with high-power objective lens

27. Function of Parts Arm: supports the body tube
Base: supports the microscope
Stage: supports the slide being used
Stage clip: holds the slide in place

28. Function of Parts
Diaphragm: controls the amount of light that comes through the stage
Mirror/Light Source: reflects light upward through diaphragm