Name: ____________________________ Block: _____
v3.1/06
CELL LAB
Comparing Animal & Plant Cells
Materials
compound microscope
razor blade
dropper
paper towel/tissue
slides and coverslips
toothpick
iodine
forceps
onion epidermis
red blood cells (in isotonic solution)
Elodea (an aquatic plant)
cheek epithelial cells (your own)
Procedure
A. ONION CELLS
Unstained cells
1. Put a drop of water on a clean slide.
2. Take a piece of onion and holding the concave side toward you, peel a transparent layer
from this surface. This is the epidermis of the onion (top layer of cells).
3. Carefully place a small piece of this layer of epidermis in the drop of water so that it lies
flat. (you may have to trim this piece with scissors or a razor blade so it fits under the
coverslip)
4. Place the coverslip over the onion piece. Never push down on the coverslip (unless you
are trying to crush your specimen).
5. Look at the cells under low power and observe their general size and shape. Draw and
label the parts indicated on the Cell Lab Data Sheet.
6. Now look at the cells under high power. Do not draw in high power, just observe.
Stained cells
7. Take the slide off the stage of the microscope and stain the onion epidermis as shown by
your teacher:
Without removing the coverslip, add a drop of iodine to the slide, next to the coverslip.
Then soak up the water under the coverslip from the opposite side with a piece of paper
towel or a tissue.
8. Make sure your onion is stained yellow. If not, add more iodine and wick from opposite
side once more. When onion is stained, add a drop of water next to coverslip and wick
through with a fresh paper towel. Do this until liquid around onion is clear.
9. Now look at the stained cells under low power. Draw and label the low power view.
Note how the cells appear different.
10. Now look at the stained cells under high power. Again, do not draw in high power, just
observe.
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B. CHEEK EPTHELIAL CELLS
1. Put a small drop of water on a clean slide.
2. With the broad end of a toothpick, gently scrape the inside lining of your cheek.
3. Deposit a little of the scraping in the drop of water by rolling the toothpick in the water.
You do not have to have a visible mass.
4. Stir the water gently to break up any clumps of cells (these will not be visible to the
unaided eye!)
5. Add a small drop of iodine stain to the cells and add a coverslip.
6. Observe under low power on the microscope.
7. Find one or two clearly visible cells, center them in your field of view, and switch to high
power. Focus under high power and draw and label on Data Sheet.
C. ELODEA CELLS
1. Put a small drop of water on a clean slide.
2. Pull off a young leaf (near the tip) from an Elodea plant.
3. Place the leaf, bottom side up, in the drop of water. DO NOT stain the leaf.
4. Look at this preparation under low power. You will see some cells that seem to be
packed with small green bodies. These bodies are chloroplasts.
5. Examine one of these cells under high power and draw and label on Data Sheet.
D. RED BLOOD CELLS
1. Put a small drop of blood cells (diluted in an isotonic salt solution) on a clean slide. You
do not have to add water since the cells are already in solution.
2. Add a coverslip and observe under low power. *These cells may be tricky to find, even
in low power. They are much smaller than any other cells you have looked at.
3. Find one or two clearly visible cells and focus under high power and draw.
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Name: ____________________________ Block: _____
v3/05
CELL LAB Data Sheet
* Remember, all microscope drawings should include: field of view, specimen
name, & total magnification. On this data sheet, the first two of these are
already provided. However, you must add the total magnification.
ONION CELLS
Label (in both drawings): Cell wall, cytoplasm, nucleus (can you see this?)
Before Staining
After Staining
Onion Cell Questions
1. What is the difference between the onion cell before and after staining with iodine?
2. Describe where in the onion cell the nucleus can be seen (what part of the cell?).
If you didn’t pay careful attention to this when looking at your last slide, go back and look at it again.
3. What is the approximate size of a single onion cell under low power (compare its length and
width to the whole field of view)? What is the approximate size of a single onion cell under high
power (compare its length and width to the whole field of view)?
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CHEEK EPITHELIAL CELLS
Label: Cytoplasm, cell membrane, nucleus
After Staining
Cheek Epithelial Cell Questions
1. Since the cheek cells were spread by a toothpick, what happened to many of the fragile cell
membranes?
2. You could probably see that many cells appeared roundish or “ellipsoid” in shape. But from
the side, the cells look relatively flat. (Did you see this? If not, go back and try to observe
this.) How do you think this flat shape is related to its function of lining the inside your
cheek? (Hint: Run your tongue on the inside of your cheek. How does the surface feel?
Why is it important that it feels this way?)
3. How does the size of a cheek cell compare to that of an onion cell? Make sure you compare
them in terms of what you observed under the same field of view.
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ELODEA CELLS
(use colored pencils on this drawing!)
Label: Cell wall, cytoplasm, chloroplasts
Elodea Cell Questions
1. What is the biggest difference that you notice between the onion cell and the Elodea cell?
(Hint: What do you see in the Elodea that you did not see in the onion?)
2. How does this structural difference between the onion and elodea leaf cells relate to their
difference in function? (What is the function of each??)
3. Frequently, you can see the chloroplasts moving around. If you see this, let your teacher and
classmates know!! What do you think is the advantage of chloroplast motion? Consider
both their function and location. Use your noggin and refer to the picture below for some clues.
4. Chloroplasts have no means of moving on their own. How do they move around in the cell?
Refer to class notes for ideas.
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RED BLOOD CELLS
Label: Cell membrane, cytoplasm
Red Blood Cell Questions
1. What is missing from the red blood cells that is present in cheek cells?
2. How is the size and shape of the red blood cell different from the cheek cells?
CONCLUDING LAB QUESTIONS
1. What parts of Cell Theory did you see some supporting evidence of during this lab? What
was that evidence?
Hint: Which aspects of Cell Theory did you directly observe?
Go back to your notes or look in a classroom textbook if you do not remember all the parts to Cell Theory.
2. If there was a part of Cell Theory that you did not directly observe, what was it? What could
you do / look at to provide evidence for this statement?
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