1. Louis Pasteur and the development of cell theory

3. Background:

4. Background:
• Francesco Redi - meat in covered jars does not produce maggots

5. Background:
• Francesco Redi - meat in covered jars does not produce maggots
• John Needham, Lazzaro Spallanzani - extensively boiled broth put in sealed,
sterilized container does not turn cloudy

6. Background:
• Francesco Redi - meat in covered jars does not produce maggots
• John Needham, Lazzaro Spallanzani - extensively boiled broth put in sealed,
sterilized container does not turn cloudy
But what if airflow is needed for
spontaneous generation to occur?

7. Louis Pasteur

9. • Boiled broth in a swan-necked flask.

10. • Boiled broth in a swan-necked flask.
• Dust from outside air could not get in
because of the long, bent neck of the flask.

11. • Boiled broth in a swan-necked flask.
• Dust from outside air could not get in
because of the long, bent neck of the flask.
• Left for a few days

13. Results:

14. Results:
• Broth remained clear, no bacteria found when examined
under microscope

15. Results:
• Broth remained clear, no bacteria found when examined
under microscope
• Dust collected in bend of swan neck

16. Results:
• Broth remained clear, no bacteria found when examined
under microscope
• Dust collected in bend of swan neck
• If flask was broken or tipped so the broth touched the
dust, the broth would go cloudy after a couple of days

17. cc licensed flickr photo by msitua: http://flickr.com/photos/
msitua/3246137819/

18. Cell Theory cc licensed flickr photo by msitua: http://flickr.com/photos/
msitua/3246137819/

19. Cell Theory cc licensed flickr photo by msitua: http://flickr.com/photos/
msitua/3246137819/
• Cells are the basic unit of life

20. Cell Theory cc licensed flickr photo by msitua: http://flickr.com/photos/
msitua/3246137819/
• Cells are the basic unit of life
• All cells come from pre-existing cells

21. Cell Theory cc licensed flickr photo by msitua: http://flickr.com/photos/
msitua/3246137819/
• Cells are the basic unit of life
• All cells come from pre-existing cells
• All living things are made of cells and cell
products

22. All cells come from pre-existing cells
cc licensed flickr photo by Andrew Coulter Enright:
http://flickr.com/photos/andrewcoulterenright/
2146798371/

23. All cells come from pre-existing cells
So where did the first cell
come from?
cc licensed flickr photo by Andrew Coulter Enright:
http://flickr.com/photos/andrewcoulterenright/
2146798371/