1. Introduction to Cells
Biology A/Cells

2. The Discovery
Cells were first discovered in 1665 when Robert Hooke observed a slice of cork under a microscope.
Hooke thought the small divisions looked like the monastery cells that monks lived in.

3. The Discovery
Anton van Leeuwenhoek was the first to observe micro- organisms in 1674, when he observed a drop of water under a microscope.

4. The Discovery Continues…
The combined work of a number of other scientists finally led to the development of the cell theory.

5. The Cell Theory All living things are made of cells.
Cells are the basic units of structure and function in living things.
New cells are only produced by other cells.

6. Micro-organisms We will discuss 3 main types of micro-organisms:
1. Viruses
2. Bacteria
3. Protists

7. Bacteria Bacteria are microscopic, single-celled organisms.
Bacteria are prokaryotes which means that their DNA is not contained inside the protective coating of a nucleus.

8. Viruses Viruses are the simplest and smallest micro-organisms.
They contain a small amount of DNA (genetic material) and a protective coat called a capsid.
Viruses reproduce by attaching to another cell and overriding normal cell functioning so that the cell produces new viruses.

9. 2 Categories of Cells
Prokaryotic Cells Eukaryotic Cells

10. Prokaryotic Cells Do not contain a nucleus
Are smaller and simpler than eukaryotic cells
Example: Bacteria

11. Eukaryotic Cells Have a nucleus
Are larger and more complex than prokaryotic cells
Contain specialized structures called organelles
Examples: Plant cells
Animal cells

13. Protists
Protists are generally larger than viruses and bacteria, but they are still microscopic.
Protists are eukaryotes, which means their DNA is contained in a protective nucleus.