1. 3.1 Cell Theory
KEY CONCEPT Cells are the Basic unit of life.

2. 3.1 Cell Theory
The cell theory grew out of the work of many scientists
and improvements in the microscope.
First to
identify cells
and name
them.
Looked at
cork.
Made more
powerful
microscopes
an first to
describe
living cells.
All three of these scientists contributed to the
cell theory.

3. 3.1 Cell Theory
• More was learned about cells
as microscopes improved.
• The cell theory is a unifying
concept of biology.
Leeuwenhoek’s
drawings of
microscopic
animalcules.

4. 3.1 Cell Theory
Early studies led to the development of the cell theory.
• The Cell theory has three principles.
– All organisms are made of cells.

5. 3.1 Cell Theory
Early studies led to the development of the cell theory.
• The Cell theory has three principles.
– All organisms are made of cells.
– All existing cells are produced by other living cells.

6. 3.1 Cell Theory
Early studies led to the development of the cell theory.
• The Cell theory has three principles.
– All organisms are made of cells.
– All existing cells are produced by other living cells.
– The cell is the most basic unit of life.

7. 3.1 Cell Theory
Prokaryotic cells lack a nucleus and most internal
structures of eukaryotic cells.
• All cells share certain characteristics.

8. 3.1 Cell Theory
Prokaryotic cells lack a nucleus and most internal
structures of eukaryotic cells.
• All cells share certain characteristics.
– Cells tend to be microscopic.
Bacterium
(colored SEM; magnification 8800x)

9. 3.1 Cell Theory
Prokaryotic cells lack a nucleus and most internal
structures of eukaryotic cells.
• All cells share certain characteristics.
– Cells tend to be microscopic.
– All cells are enclosed
by a membrane.
– cytoplasm
Bacterium
(colored SEM; magnification 8800x)
cell membrane

10. 3.1 Cell Theory
Prokaryotic cells lack a nucleus and most internal
structures of eukaryotic cells.
• All cells share certain characteristics.
– Cells tend to be microscopic.
– All cells are enclosed
by a membrane.
– All cells are filled with
cytoplasm.
Bacterium
(colored SEM; magnification 8800x)
cell membrane
cytoplasm

11. 3.1 Cell Theory
There are two cell types: eukaryotic cells and prokaryotic
cells.

12. 3.1 Cell Theory
There are two cell types: eukaryotic cells and prokaryotic
cells.
• Eukaryotic cells have a
nucleus.
nucleus
cell membrane

13. 3.1 Cell Theory
There are two cell types: eukaryotic cells and prokaryotic
cells.
• Eukaryotic cells have a
nucleus.
• Eukaryotic cells have
membrane-bound organelles.
nucleus
cell membrane
organelles

14. 3.1 Cell Theory
There are two cell types: eukaryotic cells and prokaryotic
cells.
• Prokaryotic cells do not
have a nucleus.
nucleus
cell membrane
organelles

15. 3.1 Cell Theory
There are two cell types: eukaryotic cells and prokaryotic
cells.
• Prokaryotic cells do not
have a nucleus.
• Prokaryotic cells do not
have membrane-bound
organelles.
nucleus
cell membrane
organelles
cytoplasm