1. Section 1: Discovering Cells
What are cells?
How did the invention of the microscope contribute to knowledge about living things?
What is the cell theory?
How are the cells of multicellular organisms organized?

2. Development of the Cell Theory
The cell theory states the following:
All living things are composed of cells.
Cells are the basic units of structure and function in living things.
All cells are produced from other cells.

3. Cells and Structure
The structures of living things are determined by the amazing variety of ways in which cells are put together. (i.e. a salamander’s cells form a body with a head and four legs)

4. Cells and Function Cells function similarly in all living organisms
The functions of an organism include obtaining oxygen, getting rid of wastes, obtaining food and growing.
Cells carry out these basic processes of life in similar ways

5. First observations of cells
The invention of the microscope made it possible for people to discover and learn about cells

6. Robert Hooke First compound microscope built in 1663
Looked at cork and thought the spaces resembled little “cells”

7. Anton Van Leeuwenhoek
Looked at pond water, scrapings from teeth and gums and water from rain gutters
Saw moving organisms and called them animalcules (little animals)

8. Other Scientists Virchow: all cells come from other cells (1855)
Schleiden: All plants are made of cells (1838)
Schwann: all animals are made of cells (1839)

9. Unicellular and Multicellular
Unicellular, or single-celled, organisms include bacteria, the most numerous organisms on Earth. Multicellular organisms are composed of many cells.
Unicellular
Multicellular

10. Unicellular
Made of one cell (i.e. bacteria)

11. Multicellular
Made of many cells (i.e. humans)

12. Cells are organized into:
Cells tissues organs organ systems

13. End of Section: Discovering Cells