The Cell and Cell Theory
Robert Hooke
Louis Pasteur
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“CELLS and CELL THEORY”
1. How did technology influence the development of Cell Biology?
2. With what social institution was the word “cell” associated?
3. What simple pattern did Hooke and others find as to where cells were found and not found?
4. Can you really prove that all living things are composed of cells? Why not? What does this tell you about the
nature of science and scientific investigation?
5. List the functions of life:
a.
d.
b.
e.
c.
f.
6. Why was Pasteur’s negative experiment more “powerful” than a thousand positive proofs like Dr. Scientist
made?
7. List the essential points of cell theory:
a.
b.
c.
History
In the early 1600’s, around the same time
as the pilgrims were coming to America,
the art of glassmaking was greatly
improving. By the middle of the 1600’s a
new invention called the microscope was
created using two glass lenses and a light.
Robert Hooke looks at a piece of cork
In 1665 Robert Hooke used a microscope to look at a thin slice of
cork. This is what he saw. What does it look like to you?
What are those little rooms?
To Robert Hooke those little boxes looked like tiny
rooms. He called these tiny rooms “Cells.”
Where else can we find cells?
If you were Robert Hooke’s
assistant, where would you
tell him to look next?
He looked at other trees’ bark.
Guess what he found.
He found Cells
He looked at leaves.
Guess what he found.
He found Cells
He looked at his hair…
He found Cells
He looked at his skin…
He found Cells
He looked at a rock…
He did not find Cells
He looked at some metal…
He did not find Cells
He looked at some water…
He did not find Cells
He looked at a cat’s blood…
He found Cells
He looked at a piece of
wood...
He found Cells
Why did he find cells in some
places but not in others?
1. All living things
have cells.
Not only do all living things
have cells, but they are made
of cells.
What’s the difference?
You all have a nose
but are you made of noses?
2. The cell is the smallest living
thing that can perform all the
functions of life.
1. It grows, develops, and dies
2. Uses energy
3. Needs water
4. Responds to changes in its
environment
5. Gives off waste
6. Reproduces
Science Headline News
Year 1850
Scientists prove that Maggots
come from dead meat…
Dr. Scientist proved that maggots come
from dead meat. After leaving meat out
in his laboratory Dr. Scientist noticed
that small maggots were found crawling
out of the meat. Dr. Scientist said this
proves maggots come from meat.
Do you believe that maggots
come from meat?
Louis Pasteur did not believe this.
How could he prove Dr. Scientist
wrong?
Pasteur’s experiment
Pasteur covered up some
meat and left it out. Do you
think maggots would be
found inside his meat?
No.
Pasteur concluded that fly’s
were landing on the meat and
laying eggs on the meat.
When the eggs hatched the
maggots came out.
3. Cells come from other cells
from the same species.
Summary
The cell theory consists of three
basic points:
1.All living things are made of cells.
2.The cell is the smallest living thing
that can perform all the functions of
life.
3.All cells must come from
preexisting cells.