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Names: _______________________________________________ Date: __________ Hour: ___
How Small Can You Go?
Cell Lab
Objective: To become familiar with a variety of eukaryotic cells
I. Eukaryotic Cells
All organisms other than bacteria are composed of eukaryotic cells. Eukaryotic cells are
significantly larger than the prokaryotic cells and they are structurally more complex. In addition to the
cell membrane there are numerous internal membranes that compartmentalize the cell and form
organelles. Multiple linear chromosomes (DNA) and one or more nucleoli are enclosed in membranes
forming a distinct nucleus. Membrane-bound organelles such as mitochondria, Golgi, ER, are present
but are too small to observe through a compound microscope. Variations of the eukaryotic cell exist
including cells found in plants, animals, fungi, and protests.
A. Plant Cells
Eukaryotic plant cells have slightly elastic cellulose cell wall outside the cell membrane. The
cell wall contributes shape and rigidity to the cell. Plant cells also contain a large central
vacuole filled with fluid. The central vacuole functions in maintaining pressure for the cell; it
also serves for storing waste materials. Chloroplasts also occur in the cytoplasm that contain
chlorophyll and is the site of photosynthesis.
Procedure:
Prepare and examine wet mounts of the following kinds of plant cells
1. Cork Tree
a. With a razor blade or scalpel, obtain a very thin slice of a white potato. It should be
less than 1 mm thick.
b. Under low power, observe the layers of cells. Notice how uniform the cells are
c. Draw a cork cell on the back of this lab and label the following organelles: cell wall,
chloroplast, vacuole, nucleus
2. Potato
a. With a razor blade or scalpel, obtain a very thin slice of a white potato. It should be
less than 1 mm thick. Put a large drop of water on the slide, place the potato sample in
the water, and cover with a cover slip. If the cover slip can “see saw” back and forth over
the potato, the potato is too thick.
b. Examine the slide under low and high power. Observe the conspicuous cell walls and
large oval bodies within the cells.
c. Put a drop of iodine at the edge of the cover slip and allow the iodine to diffuse under
the cover slip.
d. Re-examine the cells. What color have the oval granules become? _______________
e. Draw a potato cell on the back of this lab and label cell wall and nucleus
3. Red Onion Scale
a. Put a large drop of water on a slide. Peel back a tine section of a scale of a red onion.
Place the specimen on a slide, and cover with a cover slip.
b. Examine the colored cells under low and high power. Notice the central vacuole. It is
conspicuous because of the pigments present.
c. Is the nucleus seen? If not, add a drop of iodine to the edge of the cover slip and allow
the iodine to diffuse under the cover slip. Re-examine the cells under high power.
d. Where is the nucleus located? __________________________
e. Draw a red onion cell on the back of this lab and label cell wall and nucleus
B. Animal Cells
Animal Cells lack a cell wall. The cell is bounded only by the cell membrane. Animal cells
also lack a central vacuole and chloroplasts. Animal cells also lack centrioles, but they are not
easily observed under a compound microscope
Procedure:
Prepare and examine wet mounts of the following kinds of animal and animal-like cells. It is often
useful to close down the iris diaphragm when looking at these cells. They are virtually colorless, and
reducing the light helps to make them stand out against the background.
1. Cheek Epithelium
a. Place a drop of water on a clean slide. Obtain the epithelium cells by gently scraping
the inside of the cheek with the blunt end of a clean toothpick. Place the cells on the slide
by swirling the blunt end of the toothpick in the water. Cover the slide with a cover slip.
b. Examine the cells under low and high power. Notice the absence of a cell wall, a
central vacuole, and chloroplasts. Are all cells the same shape and size? Why _________
________________________________________________________________________
c. Draw epithelium cells on the back of this lab and label cell membrane and nucleus
2. Pond Water
a. Place a drop of water on a clean slide. Obtain a sample of pond water. Place two
drops of pond water on clean slide. Cover with a cover slip.
b. Examine the cells under low and high power. Notice objects moving in and out of the
viewing area. These are microscopic species (Protists) often found in natural ponds,
lakes, rivers, etc.
c. Draw any objects seen on this slide on the back of this lab
Questions and Analysis
1. What characteristics do prokaryotes and eukaryotes have in common? Name two
1.
2.
2. List three differences between prokaryotes and eukaryotes.
Prokaryotes
Eukaryotes
1.
2.
3.
3. List three structures that are in plant cells but not in animal cells. What is the function of each?
1.
2.
3.
4. List two structures seen in lab that are in both plant and animal cells. What is the function of each?
1.
2.
5. What is the value of adding dyes or stains to slides?
6. List two cell parts found in the nucleus.
1.
2.
7. Why weren’t other organelles like mitochondria, Golgi, and ER not seen in this lab?
8. What does a cell wall do to help a plant cell?
9. Photosynthesis occurs in what organelle?
10. What organelle helps maintain pressure in the cell?
Cork Cell
Cheek Cell
Potato Cell
Onion Cell
Pond Water