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3.1 Cell Theory
These are some things that you may think of when you think of a cell:
Cell phone
jail cell
monk’s cell
cell
They have/are: structure, small, things inside, matter, mass, made
of atoms, used by humans…
3.1 Cell Theory
Main Ideas
• Early studies led to the development of the
cell theory
• Prokaryotic cells lack a nucleus and most
internal structures of eukaryotic cells.
3.1 Cell Theory
The cell theory grew out of the work of many scientists
and improvements in the microscope.
• Many scientists contributed to the cell theory.
First to
Made better
identify
lenses for
cells and
microscopes
named them
First to note
that plants
are made of
cells
Concluded
that ALL
living things
are made of
cells
Proposed
that all
cells come
from other
cells
3.1 Cell Theory
Robert Hooke
•In 1665 he used the three-lens compound microscope to
examine thin slices of cork
•He observed that cork is made of tiny, hallow
compartments
•These compartments reminded Hooke of small rooms
found in monasteries (where monks live), so he
named them cells.
3.1 Cell Theory
•
More was learned about cells
as microscopes improved.
3.1 Cell Theory
Cells
Red
blood
cells
cork
3.1 Cell Theory
How does the size of a cell in a blue
whale compare to the size of the cell
in a tadpole?
3.1 Cell Theory
How does the size of a cell in a blue whale compare to the size of the
cell in a tadpole?
A: Most cells in a whale are the same size as in a tadpole! So what
makes a blue whale so much bigger?
A whale has far more cells.
3.1 Cell Theory
The Cell theory has three principles.
1. All living things are composed of cells.
3.1 Cell Theory
2. Cells are the basic units of structure and function in
living things.
3.1 Cell Theory
3. All cells are produced from other cells.
3.1 Cell Theory
One of the 3 principles of
cell theory is that ALL
existing cells are
produced by other
existing cells. Apply this
principle to a cut on your
arm.
(Explain what is happening throughout
the healing process)
3.1 Cell Theory
Answer
One of the 3 principles of cell theory is that
ALL existing cells are produced by other
existing cells. Apply this principle to a cut
on your arm.
You get a cut
You start to bleed
You form a scab
• Messages are sent to skin cells to
replicate
• Skin cells replicate through mitosis
New skin cells are created
Scab falls off
You are healed!
3.1 Cell Theory
All cells share certain characteristics:
3.1 Cell Theory
All cells share certain characteristics:
– Cells tend to be microscopic.
Bacterium
(colored SEM; magnification 8800x)
3.1 Cell Theory
All cells share certain characteristics:
– Cells tend to be microscopic.
– All cells are enclosed
by a membrane.
cell membrane
Bacterium
(colored SEM; magnification 8800x)
3.1 Cell Theory
All cells share certain characteristics
– Cells tend to be microscopic.
– All cells are enclosed
by a membrane.
– All cells are filled with
cytoplasm.
cell membrane
cytoplasm
Bacterium
(colored SEM; magnification 8800x)
3.1 Cell Theory
There are two cell types: eukaryotic cells and prokaryotic
cells.
•
•
•
Eukaryotic cells have a
nucleus
nucleus.
– The nucleus holds the
DNA
Have membrane-bound
organelles
organelles
May be multi-cellular
cell membrane
or single-celled
Draw
organisms
and label
picture on top of
p. 24
3.1 Cell Theory
Organelles: structures that are specialized to perform distinct
processes within a cell. The nucleus is usually the largest and
most visible organelle.
3.1 Cell Theory
Things that have Eukaryotic Cells:
PLANTS
ANIMALS
FUNGI
3.1 Cell Theory
Cytoplasm: is a jellylike substance that contains dissolved molecular
building blocks- such as proteins, nucleic acids, minerals, and ions
Bacterium
(colored SEM; magnification 8800x)
3.1 Cell Theory
•
Prokaryotic cells do not
have a nucleus.
cell membrane
•
do not have membranebound organelles
•
DNA is in the cytoplasm
•
All are microscopic,
single-celled organisms
cytoplasm
Draw and label
picture on top of
p. 24
3.1 Cell Theory
Things that have prokaryotic cells
Archaea
Bacteria