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Observing Cells Microscope Activity
All living things are made up of cells. Many cells cannot be seen without the use of a microscope and special
stains. In this activity you will use a microscope and some stains to observe and compare animal cells and
plant cells.
As you do this activity, remember how to use the microscope properly. Change the light intensity to get the
highest clarity of the cells. All drawings should be on the highest power.
Obtain the following materials:
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2 Tooth picks
Iodine
Methylene blue (stain)
Microscope
Microscope slide
Cover slip
Piece of onion
Cheek cells:
You will be making 2 slides, but only drawing cells from one of them. Read directions carefully!
1.
Gently scrape the inside lining of your cheek with a toothpick.
2.
Using the tap, place one drop of water on the microscope slide.
3.
With the toothpick, mix the cheek cells with the water on the slide.
4.
Throw the tooth pick in the garbage.
5.
Hold the cover slip at a 45 degree angle to the surface of the slide. Lower the cover slip slowly,
allowing the air to escape as you lower it.
6.
Focus up to high power.
7.
With a new toothpick, gently scrape your cheek again.
8.
Place one drop of methylene blue on a slide.
9.
With the toothpick, mix the cheek cells with the stain on the slide.
10.
Throw away the tooth pick.
11.
Hold the cover slip at a 45 degree angle to the surface of the slide. Lower the cover slip slowly,
allowing the air to escape as you lower it. Use a paper towel to remove excess stain.
12.
Focus up to high power.
13.
Make a correct biological drawing of four or five good cells.
Onion Cells:
1.
Obtain a small section of onion, and peel away a small piece of the membrane between the layers. Try
not to get any finger prints on the membrane.
2.
Place the onion skin in the centre of the microscope slide
3.
Place 1 drop of iodine on the onion skin.
4.
Hold the cover slip at a 45 degree angle to the surface of the slide. Lower the cover slip slowly,
allowing the air to escape as you lower it. Use paper towel to remove excess stain.
5.
Examine the cell under high power.
6.
Make a correct biological drawing of four or five good cells.
7.
Wash and dry your cover slips and slides.
8.
Return all equipment.
Lab Questions:
1. Describe the differences between the cheek cell that had stain and the cheek cell that did not have stain.
2. What is the purpose of stains when making microscope slides?
3. The shapes of the cells should tell you if they are plant or animal cells.
Are cheek cells plant or animal cells?
Are onion cells plant or animal cells?
4. Describe any differences that you were able to observe in the onion and cheek cells under the microscope.
5. What organelle(s) in the onion cell was/were stained by the iodine?
6. Which organelle(s) in the cheek cell were stained by the methylene blue?
7. Why are many organelles not visible in either the onion or cheek cells, even with staining?
8. Name 3 organelles that were not visible in either the onion or the cheek cells even with staining.
Biological Drawings:
Magnification:
Magnification: