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Chapter 7 Section 1
Cells
The Cell Theory
• . The Cell
Theory states
that all
organisms are
composed of
similar units of
organization
called cells.
Beginning of the Cell Theory
• In 1838, a German
botanist named
Matthias
Schleiden
concluded that all
plants were made
of cells
• Schleiden is a
cofounder of the
cell theory
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Beginning of the Cell Theory
• In 1839, a
German
zoologist named
Theodore
Schwann
concluded that
all animals were
made of cells
• Schwann also
cofounded the
cell theory
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. Schleiden and Schwann
• Matthias Schleiden
observed plants and
Theodor Schwann
observed animals.
Both of them concluded
separately that all
organisms are made of
cells.
Beginning of the Cell Theory
• In 1855, a German
medical doctor named
Rudolph Virchow
observed, under the
microscope, cells
dividing
• He reasoned that all
cells come from other
pre-existing cells by
cell division
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The Cell Theory
1. All known living things are made up
of cells.
2. The cell is the unit of structure &
function 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.
Microscopes
• Until scientists began using
microscopes they believed
diseases were caused by curses
and supernatural spirits. They
didn’t know about bacteria and
other microscopic organisms.
. Robert Hooke
• In 1663
Robert Hooke
discovered cells
in a piece of
cork, and coined
the word CELL.
• What he saw
looked like small
boxes
First to View Cells
• Hooke is
responsible for
naming cells
• Hooke called them
“CELLS” because
they looked like
the small rooms
that monks lived in
called Cells
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Cells
Van Leeuwenhoek
Anton van
Leeuwenhoek
used his single
lens microscopes
and was the first
person to
observe
3. bacteria and
protozoa.
Leeuwenhoek’s microscope
Types of Microscopes
• Compound light microscope
• Electron Microscope
–SEM
–TEM
–STM
Compound Light Microscope
• Can magnify
object up to
1500X
• This is an
onion cell at
1000x
magnification.
Electron Microscope
• Uses electron beams to magnify
structures up to 500 000 times.
• Structures inside of the cell can
be seen with electron microscope.
• SEM, TEM and STM
Compound Light Microscope
• Ocular lens
• . (eyepiece)
times objective
lens give total
magnification
• EX: 10 x 40
1.Two Basic Cell Types
• Prokaryotic Cells • Eukaryotic Cells
Mainly single
Mainly
celled organisms
multicellular
organisms,
although some
are single celled
(amoeba,algae,
yeast)
2. Prokaryotic Cell
• Prokaryotes
have no
membrane
bound
organelles.
• Example –
• bacteria cell
3 and 4. Eukaryotic Cells
• Eukaryotes –
contain
membrane
bound organelles
• Example –
plants, animals,
fungi, and
protists
Organelles
• 5. An organelle is a small
specialized structure inside
of a cell.
• An example of an organelle
is the nucleus which
controls cell functions.
Transmission Electron Microscope
(TEM)
• Can see inside a cell and the organelles
Scanning Electron Microscope
(SEM)
• Scan the surface of cell to see its 3 D shape.
. Scanning Tunneling Microscope
(STM)
• Can image atoms on the surface of a molecule.