What is Elodea?
Plasmolysis
and
Cytolysis
Elodea Cell
•
Name three structures that are
shown in this plant cell that
you would not expect to find in
an animal cell?
• The Elodea plant has
the parts that
would typically be
found in a plant cell.
In this exercise we
will identify those
parts and see what
happens when you
subject this plant to
plasmolysis.
Elodea Cell Parts
It is not possible to see the cell membrane because it is
pushed up against the cell wall. Also, the central vacuole
cannot be clearly distinguished from the cell cytoplasm.
In a living elodea cell you can “roughly” tell where the
vacuole is by where the moving chloroplasts are not able
to go.
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What is plasmolysis?
•
If you were to surround this group of plant cells with salt water
then the water inside the plant would move from where there is
more water (less salt) through the cell wall and membrane to the
outside where there is less water (more salt). This process of
water movement from a high concentration of water to a lesser
concentration of water is called osmosis. When the water
movement is out from a cell this form of osmosis is specifically
called plasmolysis.
Onion Skin Plasmolysis
Note how the cell membrane draws
inward pulling the cell contents along
with it.
Elodea Plasmolysis
• This is a view of a cell
that has undergone
plasmolysis. It is now
possible to see the
cytoplasm which has
contracted around the
chloroplasts and the other
cellular structures. Most
of the water that has left
the cell has been from the
vacuole.
Types of Solutions
Hypertonic solutions contain
higher concentrations of solutes
than those in surrounding cells
resulting in the cell shrinking in
size. Hypotonic solutions
contain lower concentrations of
solutes than those in
surrounding cells resulting in
the cell swelling. Isotonic
solutions contain equal
concentrations of solutes than
those in surrounding cells and
the cell volume remains
unchanged. The first figure
below shows the effect of these
solutions on blood cells.
2
Cytolysis/Plasmolysis
What solutions were used?
Normal Red Blood Cells
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