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Name
Date
Period
HBiology
Cell Organelle Lab
Examining Plant and Animal Cells
Introduction: Cells are the basic fundamental unit of living organisms. Cells fall into two major
divisions, prokaryotic and eukaryotic. Bacteria are prokaryotic, while plants,
animals, fungi and protists make up the latter group. Animal and plant cells share
many characteristics, however they differ in several important ways. In this lab,
you will be looking at human cheek cells, onion cells and anacharis (elodea) cells.
Hypothesis:
What structures do you expect to see in each of the cells? (To be done BEFORE LAB.)
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Materials:
Microscope
Anacharis/Elodea
Methylene Blue
Slides
Toothpick
Pipette
Coverslips
Paper towel
Onion sliver
Part One: Elodea Cells
1. Obtain materials listed above
2. Prepare a wet mount slide of an Elodea leaf (one leaflet is all you need )
a. Take leaflet
b. Place on clean slide
c. Add one drop of water from the pipette to the slide
d. Gently cover the leaflet with the coverslip
3. Check your microscope. Make sure it is plugged in and that it is in low power
4. Place the slide on the stage and secure with stage clips
5. Observe the specimen in low power, focus by using the coarse and fine adjustment
6. Find a portion of the slide where the cells are distinct and switch to high power
***Do NOT use the coarse adjustment in high power***
7. Observe the small, oval, green bodies that appear in the cells. These are the chloroplasts.
8. Locate the cell wall and vacuole
9. Sketch the cells on the data sheet in the box labeled Elodea cells and label as many parts as you can
10. Remove the Elodea slide from the microscope. Place Elodea and coverslip on paper towel, rinse and dry slide
Magnification = __________X
Part Two: Onion Cells
1. Obtain a sliver of onion from the front table. Using a scalpel, remove a single layer from
the inside of an onion scale. It must be thin enough to let light pass through. It will
resemble skin peeling off after a sunburn.
2. Prepare a wet mount slide of the onion sliver. (Cover with a coverslip.)
3. Stain the specimen with iodine. To do this, place one drop of iodine on the edge of the
coverslip. Touch the opposite side with a paper towel or lenspaper. This will draw the stain
under the coverslip and onto the specimen.
4. Examine the onion cells under low power and draw them exactly as you see them, labeling
each organelle you are able to identify (look for the nucleus, cell wall, chloroplasts, and
vacuole). Next to each organelle you identify, please describe its function in the cell.
Magnification = __________X
5. Switch to high power (adjust by CHANGING ONLY THE FINE FOCUS) and look at the cell
a second time. Draw a cluster of at least four onion cells; label each organelle you are able
to identify and identify the function if you haven’t done so in step 4.
Magnification = __________X
Part Three: Cheek Cells
1. Gently scrape the inside of your cheek with a toothpick, transfer these cells onto a clean
microscope slide into a drop or two of water.
2. Stain these cells with bromoblue or methylene blue according to the technique described
above.
3. Examine your cheek cells under low power and draw them exactly as you see them, labeling
each organelle you are able to identify (look for the nucleus, cell membrane and cytoplasm).
Next to each organelle you identify, please describe its function in the cell.
Magnification = __________X
4. Switch to high power (adjust by CHANGING ONLY THE FINE FOCUS) and look at the cell
second time; drawing exactly what you see; label each organelle you are able to identify and
identify the function if you haven’t done so in step 3.
Magnification = __________X
Clean up: Please dispose of all coverslips and onion slivers. Carefully rinse the microscope slides off
with water and place them into the DEATH BEAKER. Adjust the microscopes back to low
power and place them back into the cabinets.
Analysis:
Although you are not required to answer in complete sentences, please make sure that your answer to each question is clear
and complete.
1.
Classify each of these cells as prokaryotic or eukaryotic. Give reasons for your answer.
2. What organelles did you see in your plant cells that you didn’t see in your cheek cells? What
organelles did you see in your cheek cells that you didn’t see in your onion and elodea cells?
3. Was it difficult to see the cell membrane in the onion cells? The elodea cells? The cheek cells?
Why or why not?
4. What is the general location of the nucleus in a plant cell? An animal cell?
5. How were the three cells similar? How were they different?
6. Most likely, you were not able to see structures like the Golgi apparatus, the endoplasmic
reticulum and the mitochondria. Why? Give an estimate as to how small they might be in
relation to the entire cell.
7. Why do you think we added the stain to the cell specimens? (Hint: did anything change color
from your original specimen?)