Preparing Unstained Red Onion Cells for a
Microscope Slide
Method
1.
Cut off a small piece of red onion
2.
Use forceps or your fingernail to peel away a very thin layer of skin from the inside
3.
Spread and smooth the onion skin flat on the middle of the microscope slide
4.
Add 2 - 3 drops of distilled water
5.
Carefully place a cover slip over the skin
6.
Gently dab the edges with a paper towel to absorb any excess solution
7.
Place the microscope slide onto the stage and secure with the stage clips
8.
Ensure the magnification is at the lowest setting to begin with (usually 4x or 10x)
9.
Use the adjustment knobs to focus on and observe the cell at a higher magnification
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Preparing Stained Onion Cells for a Microscope Slide
Method
1.
Cut off a small piece of onion
2.
Use forceps or your fingernail to peel away a very thin layer of skin from the inside
3.
Spread and smooth the onion skin flat on the middle of the microscope slide
4.
Add 2 - 3 drops of distilled water
5.
Add 2-3 drops of methylene blue (or other stain)
6.
Carefully place a cover slip over the skin
7.
Gently dab the edges with a paper towel to absorb any excess solution
8.
Place the microscope slide onto the stage and secure with the stage clips
9.
Ensure the magnification is at the lowest setting to begin with (usually 4x or 10x)
10. Use the adjustment knobs to focus on and observe the cell at a higher magnification
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Preparing Unstained Onion Cells for a Microscope Slide
Use a sharp pencil and draw an accurate diagram of your sample.
Try not to sketch. Use simple lines.
Clearly label the different parts of the cell you can identify.
Questions:
1. Which organelles can you identify on the cell?
2. Which organelles did you expect to see, but cannot?
3. Why is it important to start your observations using the microscope on the lowest
magnification setting?
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Answers
Preparing Unstained Onion Cells for a Microscope Slide
Use a sharp pencil and draw an accurate diagram of your sample.
Try not to sketch. Use simple lines.
Clearly label the different parts of the cell you can identify.
Questions:
1. Which organelles can you identify on the cell?
Cell wall, cell membrane, nucleus, cytoplasm
2. Which organelles did you expect to see, but cannot?
Chloroplasts, vacuole, mitochondria
3. Why is it important to start your observations using the microscope on the lowest
magnification setting?
To avoid breaking the microscope slide with the objective lens
Photo courtesy of kaibara87 (@flickr.com) - granted under creative commons licence