3.1 Cell Theory
KEY CONCEPT Cells are the Basic unit of life.
3.1 Cell Theory
The cell theory grew out of the work of many scientists
and improvements in the microscope.
• Many scientists contributed to the cell theory.
3.1 Cell Theory
In the 1600’s he was the first scientist to describe
living cells using a simple microscope (contained
one lens).
Anton van Leeuwenhook
3.1 Cell Theory
• He was an English scientist who
lived at the same time as van
Leeuwenhoock.
•Hooke was the first to identify cells
and name them.
• He observed that cork was
composed of tiny, hollow boxes that
he called “CELLS”.
Robert Hooke
3.1 Cell Theory
German scientist who observed many types of plants and
determined that all plants consist of cells.
Matthias Schleiden
3.1 Cell Theory
German scientist who determined that all animals consist
of cells.
Theodor Schwann
3.1 Cell Theory
Rudolf Virchow
• Proposed that all cells come from other cells.
3.1 Cell Theory
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.
3.1 Cell Theory
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.
3.1 Cell Theory
The History of the Cell Theory
Before microscopes were invented, diseases were thought to be
caused by curses and supernatural events.
By using microscopes scientists realized they were entering a
new world---one of microorganisms.
Microscopes enabled scientists to view and study cells.
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.
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.
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.
3.1 Cell Theory
All cells share certain characteristics.
3.1 Cell Theory
All cells share certain characteristics.
– Cells tend to be microscopic.
Bacterium
(colored SEM; magnification 8800x)
3.1 Cell Theory
All cells share certain characteristics.
– Cells tend to be microscopic.
– All cells are enclosed
by a membrane.
cell membrane
Bacterium
(colored SEM; magnification 8800x)
3.1 Cell Theory
All cells share certain characteristics.
– Cells tend to be microscopic.
– All cells are enclosed
by a membrane.
– All cells are filled with
cytoplasm.
cell membrane
cytoplasm
Bacterium
(colored SEM; magnification 8800x)
3.1 Cell Theory
There are two cell types: eukaryotic cells and prokaryotic
cells.
3.1 Cell Theory
There are two cell types: eukaryotic cells and prokaryotic
cells.
Eukaryotic cells have a nucleus.
nucleus
cell membrane
3.1 Cell Theory
There are two cell types: eukaryotic cells and prokaryotic
cells.
Eukaryotic cells have a nucleus.
nucleus
Eukaryotic cells have membranebound organelles.
organelles
(multi-cellular organisms)
cell membrane
ex. -humans
-other animals
3.1 Cell Theory
There are two cell types: eukaryotic cells and prokaryotic
cells.
• Prokaryotic cells do not
have a nucleus.
nucleus
organelles
cell membrane
3.1 Cell Theory
There are two cell types: eukaryotic cells and prokaryotic
cells.
• Prokaryotic cells do not
have a nucleus.
nucleus
• Prokaryotic cells do not
have membrane-bound
organelles.
• AKA (Unicellular organisms)
ex. bacteria
organelles
virus
cell membrane
cytoplasm