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History of the Cell
How are these cells the same and
how are they different?
What is a cell?
A cell is the basic unit of life.
A cell is a structure within a living thing that has
a boundary surrounding the material inside.
How small is a cell?
How were cells discovered?
Scientists were curious about
what living things were made
of.
So they created microscopes
to take a closer look at living
things.
Who were the main people
involved in the discovery of cells?
Anton van Leeuwenhook
Robert Hooke
Robert Brown
Matthias Schleiden
Theodor Scwann
Rudolf Virchow
Anton von Leeuwenhoek
1600s.
First to see and describe cells.
Used a simple microscope (one lens).
Looked at tiny living organisms in a drop of
pond water (“wee beasties”).
Robert Hooke
1665.
First to use the term,
“cells.”
Used a compound
microscope (2 lenses).
Looked at a slice of cork
(dead cells).
Noted for seeing,
describing, and explaining.
Robert Brown
1831.
First to identify the nucleus.
Realized that nucleus was doing something
important.
Matthias Schleiden
1838.
First to conclude that all plants are made of
cells.
Theodor Schwann
1839.
First to conclude that all animals are made of
cells.
Rudolf Virchow
1855.
Cells reproduce: that
is where new cells
come from.
“When a cell exists,
there must have been
a pre-existing cell…”
What is the Cell Theory?
1. All living things are made of cells.
(Schleiden = plants, Schwann = animals)
2. Cells are the basic units of structure and
function in living things.
3. New cells are produced from existing
cells.
(Virchow)
Prokaryotes and Eukaryotes
Word origins
eu…..
means ‘true’
pro….
Means ‘earlier than’
karyon….. means ‘kernel’
organelle…means ‘mini-organ’
Cells Come in a Variety of Shapes
and Sizes
 Most cells = 5 to 50 µm in diameter
 Smallest= mycoplasma bacteria
(0.2 µm in diameter)
 Largest = Chaos chaos amoeba
(1000 µm in diameter)
Size
Nucleus
Genetic
Material
Example
Prokaryotes
Usually
smaller and
simpler
Usually larger and
more complex
Absent
Present
Not in
nucleus
Bacteria
Eukaryotes
In nucleus (separate
from rest of cell)
Plants, animals,
fungi, protists
Prokaryotic and Eukaryotic Cells
Cell membrane
Cytoplasm
Prokaryotic Cell
Cell membrane
Cytoplasm
Nucleus
Eukaryotic Cell
Organelles
4
Prokaryotic Cell Parts: Bacteria