Cheek Cell Lab
Problem: What are you made out of?
Background: One main difference between plant cells and animal cells is that plant cells have a
cell wall and animal cells do not. A good analogy to think of is an egg with a shell (plant cell)
and an egg without a shell and just the membrane (animal cell). The lack of a cell wall gives
animal cells a globular, spherical shape. When you look at your cheek cells, you are looking at
little building blocks of you!
Hypothesis (a statement predicting the outcome of the problem being tested).
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Materials
lab sheet
toothpick
iodine
cheek cells
glass slide
cover slip
microscope
Procedure:
1. Add one drop of methylene blue or iodine to the middle of a clean slide. Be careful!
Methylene blue/iodine will stain your clothes and skin.
2. Use the flat side of a toothpick to gently scratch the inside of your cheek. DO NOT GOUGE
YOUR CHEEK. You don’t need chunks of skin and definitely don’t want to draw blood.
3. Gently touch the toothpick o the drop of dye on the slide. Some of your cheek cells should
drift off into the dye. Throw the toothpick away.
4. Slowly lower the side of the cover slip until it covers the dye completely. Make sure there are
no air bubbles.
5. Make sure the lowest power objective (4X) is in place over the stage and the microscope light
is turned on. Place the slide onto the stage of the microscope.
6. Look through the eyepiece and turn the course adjustment knob until an image comes into
focus. It should look like scattered blobs. Move the slide around until a nice cluster of blobs
moves into the center of view.
7. Rotate the objective to the next highest power. If you need to, use the fine adjustment knob to
get the image into focus. You may see a small dot in the middle of each cell.
8. In your observations, draw a color picture of what you see. Label the picture “Human cheek
cells 100X.” Label as many parts of the cell as you can see.
9. In your observations, draw a color picture of what you see. Label the picture “Human cheek
cells 400X.” Label as many parts of the cell as you can see.
11. When finished, wipe your slide clean with a paper towel and place the towel in the trash.
Set your clean slide and cover slip aside for the next class to use.
100X:
Approximate dimensions of a
cheek cell: _________________
Qualitative Observations:
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400X:
Approximate dimensions of a
cheek cell: _________________
Qualitative Observations:
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Conclusion (1. restate purpose, 2. was your hypothesis correct or incorrect, 3. give an example of what
happened, 4. why do you think it happened that way, 5. tell what you learned, 6. how would you do this differently?)
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