Cell Theory
Presented by Kesler Science
Essential Questions:
1. What is the cell theory?
2. What are similar functions of all
cells?
Quick Action – INB Template
Cell Theory
Cell Theory INB
Template
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2.
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4.
Cut out the Template on
the solid lines
Glue outside tabs into
notebook
Opens like windows
Write notes underneath
window panes
Robert Hooke
What is
the cell
theory?
Matthias
Schleiden,
Theodor
Schwann, &
Rudolph
Virchow
What are
the 2 main
types of
cells?
Cell Theory
Cell
• Smallest structural and
functional unit of an organism
• Usually microscopic
• Contains cytoplasm and a
nucleus enclosed in a
membrane
• Two main types of cells:
1. Prokaryotic (no nucleus)
2. Eukaryotic (has a nucleus)
Cell Theory
Robert Hooke
• Observed bark of cork trees
under a microscope
• Thought the objects looked
liked individual rooms in a
monastery, which were called
cells
• Called his discovery cells
• Did not know their true function
Cell Theory
Anton van Leeuwenhoek
• Developed the microscope
lens to see greater
magnification
• First person to observe bacteria
and protozoa (single-celled
animal)
• Observed and described red
blood cells
1670
Cell Theory
Mathias Schleiden
• Concluded all plant tissues
are composed of cells
• Declared that the cell is the
basic building block of all
plant matter.
• Sensed the importance of
the nucleus of a cell
• 1838
Cell Theory
Theodor Schwann
• Concluded that all animal
tissues are composed of
cells, too.
• Collaborated with
Schleiden to form a new
theory in biology
• 1839
Cell Theory
Cell Theory
• Schleiden and Schwann’s
ideas became known as
the cell theory.
1. All organisms are
composed of cells.
2. Cells are the basic unit of
life.
• This theory was as important
to biology as the atomic
theory was to chemistry.
There was one more piece of
the puzzle to cell theory. Where
did these cells come from?
Cell Theory
Rudolph Virchow
• Proposed that all cells
result from the division
of previously existing
living cells
• This idea became a key
piece of the modern
cell theory.
• 1855
Cell Theory
Modern Cell Theory
1. All organisms are
composed of cells.
2. Cells are the basic
unit of life.
3. All cells come from
the division of
previous existing cells.
Quick Action – Cell Theory
That’s a lot of scientists to remember with very long names. Work with a
partner and come up with some sort of device to remember the
importance of each one in the development of cell theory.
Share your creative device with the class.
• Robert Hooke – named the cell base observations on cork bark
• Anton van Leeuwenhoek – improved the microscope and observed
bacteria and one-cell animals
• Mathias Schleiden – all plant tissue is made of cells
• Theodor Schwann – all animal tissue is made of cells
• Rudolph Virchow – all cells come from preexisting cells
Cell Theory
Functions of Cells
• Metabolism- chemical
reactions inside the cell
• Response – perceiving
and responding to
changes in the
environment
• Homeostasis – keeping
conditions inside the
organism within tolerable
limits (balanced)
Homeostasis
Cell Theory
Growth
Functions of Cells
(continued)
• Growth – increase in size
• Reproduction –
producing offspring
(sexually or asexually)
• Nutrition – Obtaining
food to provide energy
for growth
• Defense – protection
against enemies
Quick Action – Cell Theory
Let’s see how good you memory is.
There were 7 cell functions listed on the last two slides.
Have your teacher give you another peek at them and
then write down as many as you can remember.
Check for Understanding
Can you…
1. Recognize that according to cell theory all
organisms are composed of cells?
2. Recognise that cells carry on similar functions.