1. KEY CONCEPT Cells are the Basic unit of life.

2. The cell theory grew out of the work of many scientists and improvements in the microscope.
Many scientists contributed to the cell theory.
Wacky History of Cells

3. 1665: Hooke was the first to identify cells, and he named them.
Fig. Hooke observed the cell walls of dead plant cells

4. The cell theory grew out of the work of many scientists and improvements in the microscope.
Many scientists contributed to the cell theory.
More was learned about cells as microscopes improved.
The cell theory is a unifying concept of biology.
Fig. Leeuwenhoek observed and drew microscopic life, which he called animalcules, in pond water

5. Schleiden, Schwann and Virchow
1838: Schleiden was the first to note that plants are made of cells. 1839: Schwann concluded that all living things are made of cells. 1855: Virchow proposed that all cells come from other cells.

6. Early studies led to the development of the cell theory.
The Cell theory has three principles.
1. All organisms are made of cells.

7. Early studies led to the development of the cell theory.
The Cell theory has three principles.
2. All existing cells are produced by other living cells.

8. Early studies led to the development of the cell theory.
The Cell theory has three principles.
3. The cell is the most basic unit of life.
Summarize: Explain the 3 major principles of cell theory in your own words. Explain what it means to be a theory.

9. All cells share certain characteristics.
Cells tend to be microscopic.
All cells are enclosed by a membrane.
All cells are filled with cytoplasm.
Have DNA/RNA
Ex: bacteria cell
Top: animal cell
Left: plant cell

10. There are two cell types: eukaryotic cells and prokaryotic cells.
Eukaryotic cells have a nucleus and other membrane bound organelles like mitochondria or ER
Example: protist cells, plant cells, animal cells, fungi cells
nucleus
organelles
cell membrane

11. Prokaryotes are a lot smaller in size compared to eukaryotes.
Prokaryotic cells lack a nucleus and most internal structures of eukaryotic cells.
Prokaryotic cells do not have membrane bound organelles. No mitochondria, chloroplast, ER, etc…
All reactions in a prokaryotic cell take place in the cytoplasm of the cell.
cell membrane
Prokaryotes are a lot smaller in size compared to eukaryotes.
cytoplasm
Figure: In prokaryotic cells, such as a bacterium (above), DNA is suspended in the cytoplasm. In eukaryotic cells, the nuclear envelope separates DNA from the cytoplasm.
Summarize: What characteristics are shared by most cells? Differentiate between eukaryotes and prokaryotes.