Chapter 7
Section 1
Discovery of Cells
The Cell Theory
• The Cell
Theory states
that all
organisms are
composed of
similar units of
organization
called cells.
Before the Cell Theory people
believed in spontaneous
generation which means living
things come from non living thing
Two scientist disproved
spontaneous generation.
Francisco Redi proved that
macroorganisms do not
spontaneously generate
People
thought that
maggots
came from
meat.
• Redi
disproved
this in a
controlled
experiment
Pasture proved that microoganisms
do not spontaneously generate
Pasture
Development of Cell Theory
• Theodor Schwann and
Matthias Schleiden are
credited with coming up
with the Cell Theory
Schwann
•
Animal
Cells
Schleiden
• Plant
Cells
The Cell Theory
1. All known living things are made up
of cells.
2. The cell is structural & functional
unit of all living things.
.
3. All cells come from pre-existing
cells by division.
(No spontaneous generation ).
Microscopes
• The Cell Theory would not
exist if it wasn’t for the
development of the
microscope and the work of
others.
Janssen
• Invented the
first
compound
microscope
Robert Hooke
• In 1663 an
English scientist,
Robert Hook
improved
Janssen’s
invention.
Hooke
• Hooke observed cork
– the remains of dead
tree bark
• Coined the word
CELL
• Derived from the Latin
'cellula' which means
small compartment.
Van Leeuwenhoek
• Ten years later
Anton van
Leeuwenhoek
used his own
single lens
microscopes and
was the first
person to observe
bacteria and
protozoa.
Leeuwenhoek’s Microscope
• Leeuwenhoek
microscopes
resemble high
power
magnifying
lenses.
Compound Light Microscope
• Ocular lens
times
objective lens
give total
magnification
Two Basic Cell Types
• Prokaryotic Cells • Eukaryotic Cells
Mainly single
Mainly
celled organisms
multicellular
organisms,
although some
are single celled
(amoeba,algae,
yeast)
Prokaryotic Cell
• Prokaryotes
have no
membrane
bound
organelles.
• Example –
bacteria cell
Eukaryotic Cells
• Eukaryotes –
contain
membrane
bound organelles
• Example – plant
and animal cells
Organelles
• An organelle is a small
specialized structure inside
of a cell.
• An example of an organelle
is the nucleus which
controls cell functions.