1. The Diversity of Cells

2. Life Comes From Life
Four hundred years ago, people believed that life could suddenly appear from non-living matter.
Flies from rotting meat
Frogs from muddy ponds
Mice from straw
Spontaneous generation – the mistaken idea that living things arise from non-living sources.

3. Francesco Redi Italian doctor
In mid-1600s, designed a controlled experiment to show that flies don’t spontaneously come from decaying meat.

4. Louis Pasteur French chemist
Many people continued to believe that spontaneous generation occurred in bacteria.
Finally disproved idea of spontaneous generation

5. What is this??
Describe the images below. Be descriptive in your observations!
What do you think this is?

6. “Cells”
Thin slice of cork described as “cells”

7. Cells All living things are made of tiny structures called cells.
the smallest unit that can perform all the processes necessary for life
Because of their small size, cells weren’t discovered until microscopes were invented (1590).

8. The Microscope
Microscope – an instrument that makes small objects look larger.
Simple – 1 lens; ex: hand lens
Compound – more than one lens
Video: The Wacky History of the Cell Theory

9. Cell Theory Chart
Why could scientists not study cells before the mid-1600s?
Our understanding of cells developed over time and from the contributions of several scientists. For each of the scientists below, describe his/her contribution to our understanding of cells and the year the contribution took place. Use pgs of your textbook to complete:
SCIENTIST
CONTRIBUTION
YEAR
Hooke
Leeuwenhoek
Schleiden
Schwann
Virchow

10. Robert Hooke 1665 One of the first people to observe cells
Observed thin slice of cork under a microscope
Looked like tiny rooms, or “cells”
These were dead plant cells
Also looked at living cells
Plants & fungi
Both have cell walls; visible under microscope
Could not see animal cells due to lack of cell wall
Thought animals were not made of cells

11. Anton van Leeuwenhoek 1673 Dutch merchant who made his own microscope
Looked at pond scum & saw small “animalcules” (little animals)
Unicellular Protists
Also looked at blood cells, bacteria, yeast

12. Matthias Schleiden 1838 Studied plants
Concluded that all plants are made of cells.

13. Theodor Schwann
1839
Concluded that all animals are also made up of cells.
Wrote the first two parts of the Cell Theory:
All organisms are made of one or more cells.
The cell is the basic unit of all living things.

14. Rudolf Virchow
1858
Stated that new cells are formed only from existing cells
Third part of the Cell Theory:
3. All cells come from existing cells.

15. The Cell Theory
All organisms are made of one or more cells.
The cell is the basic unit of all living things.
All cells come from existing cells.
Cell Theory Chart:
Beside each part of the cell theory, write the name of the scientist(s) whose work contributed to that part.

16. Questions Discuss/Answer the following questions:
How did more than one scientist contribute to the creation of the cell theory?
Why is it important that the research and experiments of more than one person led to the development of the cell theory?
Do you think that the cell theory would be as widely accepted by other scientists if only one person had written it? Explain your response.
Based on the dates from your chart, about how many years did the development of the cell theory take?

17. Summary Ticket-Out-the-Door: 3 parts of the Cell Theory
2 scientists and their contributions
1 new thing you learned from the video clip