1. The Cell Theory
History
Theory
Cell Types

2. Some Cell Facts
The average human being is composed of around 100 Trillion individual cells!!!
There are over 200 different kinds of cell in your body
The biggest cells are nerve cells which can be greater than a metre and be seen even without a microscope.
Every cell in your body has the exact same instructions.
If the DNA in a single human cell were stretched out and laid end-to-end, it would measure approximately 2 meters . The average human body contains approximately 200 billion kilometers of DNA distributed among the 100 trillion cells.

3. Discovery of Cells
1665- English Scientist, Robert Hooke, discovered cells while looking at a thin slice of cork.
He described the cells as tiny boxes or a honeycomb
He thought that cells only existed in plants and fungi

4. Anton van Leuwenhoek
1673- Used a handmade microscope to observe pond scum & discovered single-celled organisms
He called them “animalcules”
He also observed blood cells from fish, birds, frogs, dogs, and humans
Therefore, it was known that cells are found in animals as well as plants

5. Year Gap???
Between the Hooke/Leuwenhoek discoveries and the mid 19th century, very little cell advancements were made.
This is probably due to the widely accepted, traditional belief in Spontaneous Generation.
Examples:
-Mice from dirty clothes/corn husks
-Maggots from rotting meat ? = +

6. 19th Century Advancement
Much doubt existed around Spontaneous Generation
Conclusively disproved by Louis Pasteur
Ummm, I don’t think so!!!

7. Development of Cell Theory
1838- German Botanist, Matthias Schleiden, concluded that all plant parts are made of cells
1839- German physiologist, Theodor Schwann stated that all animal tissues are composed of cells.

8. Development of Cell Theory
1858- Rudolf Virchow - after extensive study of cellular pathology, concluded that cells must arise from preexisting cells.

9. The Cell Theory Complete
The 3 Basic Components of the Cell Theory were now complete:
1. All organisms are composed of one or more cells.
2. The cell is the basic unit of life in all living things.
3. All cells are produced by the division of preexisting cells.

10. The Two Main Types of Cells
Prokaryotes
No nucleus
Very simple organisms
Archaea and Bacteria
Eukaryotes
Contains a nucleus
Are much larger
More complex organisms
Protists, fungi, animals and plants

11. Check it out
Cell Gallery – Check it out