Name: ________________________
Date: ___________
Block: ________
Ogling at Organelles – Lab # 2
Background: The cell is the basic unit of life, and all cells contain organelles. Every cell is
categorized as eukaryotic except for bacteria. Eukaryotic cells are often classified as either planlike or animal-like based upon the characteristics they possess. While all organelles cannot be
viewed through the compound light microscopes that we use in class, many of the important
differences can be observed. Looking at living, or “fresh” samples of tissues can allow one to
observe some of these classic differences.
Hypothesis: When examining live samples of plant and animal cells, I believe that the most
obvious difference will be: _____________________________________________________
Materials:
Glass slides & cover slips
Microscope
Lens paper
Toothpicks
Onion
Elodea
Lettuce*
Crystal violet stain
Clear tape
Pipette
Procedure:
Part A: The Onion
1. Peel a thin, clear layer of onion skin from the inside of a piece of onion.
2. Place the layer of onion skin smoothly onto a clean glass slide. Remove any bumps.
3. Make a wet mount slide by placing 2 drops of water onto the onion skin and then placing a
cover slip over the specimen.
4. Apply one drop of crystal violet stain at the edge of the cover slip. Place a folded piece of
paper toweling on the other side of the cover slip to “pull” the stain through.
5. Repeat step 4 using 2-3 drops of water instead of the stain to “wash” away the extra stain.
6. Place the onion skin under the microscope and record your data.
Part B: Elodea
1. Use forceps to carefully pull off one leaf from the Elodea sprig and place it on a clean glass
slide.
2. Make a wet mount slide of this specimen (see instructions, Part A, # 3).
3. Examine this slide under the microscope and record your data.
Part C: The Wrist
1. Carefully remove a piece of clear tape, taking care to not put fingerprints in the middle of the
surface area.
2. Place the piece of tape on your wrist area and press firmly.
3. Remove the tape from your wrist and place it sticky side up onto a clean glass slide.
4. Add 2 drops of stain onto the area where the wrist cells are. Blot to remove excess stain.
5. Add 2-3 drops of water to rinse off the stain.
6. Add 2 drops of water onto the tape specimen, add a cover slip, and view under the
microscope.
7. Record your data.
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Name: ________________________
Date: ___________
Block: ________
Part D: The Cheek
1. Using a clean toothpick, gently rub it back and forth on the inside of your cheek.
2. Smear the tip of the toothpick in the middle of a clean glass slide. Place the toothpick
immediately into the trash can.
3. Make a wet mount slide of this specimen (see Part A, # 3).
4. Use crystal violet stain to color the specimen and make the cells more visible
(see Part A, # 4-5).
5. Place the specimen under your microscope and record your data.
6. Place both the slide and cover slip in the soapy bin when you are finished.
Part E: Lettuce
1. Using forceps, peel off a layer of cells from a piece of lettuce
2. Place the layer of cells carefully onto a clean glass slide. Smooth out any bumps.
3. Make a wet mount slide of this specimen (see Part A, # 3).
4. Observe your specimen under your microscope and record your data.
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Name: ________________________
Date: ___________
Block: ________
Data Analysis Questions:
1. The specimens observed in today’s lab that were plants are:
2. The specimens observed in today’s lab that were animals are:
3. What structures were most obvious in the plant cells?
4. Were you able to observe a nucleus in every cell? Why or why not? Explain.
4. What color was the cytoplasm in the cells you observed?
5. Did you observe any vacuoles? If so, in which cells?
6. Some cell specimens had a thick outer covering. What is this “covering”, and which
specimen(s) had it?
7. If you were a single cell living in a dry desert with only sunlight, sand, and a little water, which
cell type would you need to be in order to survive? Why? Explain.
8. List or describe 4 differences between plant and animal cells.
9. How are the ribosomes and nucleolus related?
10. Are these cells prokaryotic or eukaryotic? How do you know?
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