THE
CELL
LAB
DO NOT WRITE ON THIS CLASS SET!
Do your work on the Student Report Page and a separate sheet of paper.
PURPOSE: TO OBSERVE, STUDY, DRAW, AND LEARN ABOUT DIFFERENT TYPES OF CELLS.
OBJECTIVE: when you finish this lab you should be able to:
1. Determine whether cells are prokaryotic or eukaryotic
2. Prepare a wet mount slide.
3. Describe structure and function of cell organelles
4. Distinguish plant or animal cells on the basis of their structure
5. Use a stain to highlight certain cell structures
MATERIALS:
Microscope
Razor Blade
SPECIMENS:
CORK
ONION
ELODEA
Slides
Dropper
Cover Slip
Lens Paper
CHEEK CELLS
OSCILLATORIA
POTATO
Toothpick
Iodine Stain
RED PEPPER
LACTOBACILLUS
GLOEOCAPSA
IMPORTANT DIRECTIONS FOR DRAWING:
1.
2.
3.
4.
5.
Make all drawings at the highest magnification possible.
For each specimen, do not fill the circle (Field of View) with cells. Just draw four cells for each.
These four cells must be clear drawings. Take your time and draw what you see. Cartoons and
diagrams of cells will not receive full credit.
All drawings must be the size that you see them in the Field Of View. Do not draw them larger or
smaller than they appear in the microscope.
Drawings should include the following information:
a. The magnification used while drawing the cell: 400x
b. Appropriately labeled cell structures from the following list:
cell membrane
cell wall
chloroplast
nucleus
cytoplasm
chromoplast
amyloplast
vacuole
PROCEDURE:
A. CORK CELLS: (one drawing)
1. With the single edged razor blade shave a very thin slice from a piece of
cork, the thinner the better. Remember light must pass through your
slice in order for you to see it under the microscope. CAUTION:
Cutting edges can cause serious injuries.
Always cut away
from yourself and others. Immediately return the razor blade
when you are done with it.
2. Prepare a wet mount slide of the cork slice. On a clean slide place a
drop of water and your cork specimen. Lay the coverslip on at a 45degree angle to avoid trapping air bubbles.
3. View under the highest power possible. Look closely. Draw your
specimen in the ANALYSIS section. Answer questions 1 thru 3.
B. PROKARYOTIC CELLS: Lactobacillus from a yogurt culture.
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1. These specimens will be set up for you ahead of time. They will be
magnified 1000 times, don’t touch the coarse adjustment knob.
2. Answer question 4.
C. Prokaryotic Cells: Oscillatoria and Gloeocapsa examples of blue-green
algae.
1. Make a wet mount slide of Oscillatoria and Gloeocapsa.
2. Observe under 100x and 400x
3. Divide the circle provided for your drawings on the Student Report page.
Draw and label Oscillatoria on the left half and Gloecapsa on the right
half.
4. Draw each in the space provided on the Student Report page using the
highest magnification possible and still see the whole cells. Label your
drawings.
5. Answer questions 5 through 8
EUKARYOTIC PLANT CELLS
D. ONION CELLS: (two drawings)
1. Put a drop of water on the center of a clean dry slide.
2. Get a small slice of onion from the supply area. You must use the shiny
layer of tissue that is on the outside of the onion slice. Hold your slice
of Onion with its concave (inward curve) side away from you. You will be
using the tissue that is on the side of the onion that is now facing you.
With your thumbs and fingers, snap the piece of onion as demonstrated
by Mr. D. Use your scissors to cut off a small piece, about the size of a
pencil eraser.
3. Using your scissors and forceps transfer the small piece of onion tissue
to the drop of water on your slide. Make sure the membrane is flat
and not folded. Spread out with forceps if necessary. Add the cover
slip and avoid trapping air bubbles.
4. Examine your onion tissue under low, medium, and high power.
Remember to keep your light level low.
5. Draw your unstained specimen in the ANALYSIS section. Answer
questions 9 and 10 on onion cells.
6. Remove the slide from the microscope stage.
7. Add iodine stain to the cells using the following technique:
a. Place one drop of iodine at the edge of the cover slip.
b. Hold a small piece of paper towel on the edge of the other side of
the cover slip. The stain will be pulled under the coverslip and
onto the specimen.
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8. Examine the stained onion cells under low and high power. Draw the
stained onion cells on high power and answer questions 11
through 14.
E. ELODEA CELLS: (one drawing) Elodea is a common pondweed often used
to study photosynthesis and plant cell structure.
1. Remove a young leaf from the tip of a sprig of ELODEA.
2. Prepare a wet mount slide with a cover slip. You will need 2 or 3 drops
of water.
3. Observe the Elodea cells on low and medium power. You may not be able
to get to high power because of the thickness of the Elodea leaves.
4. Look for the Chloroplasts, thy are the green bodies that are suspended
in cytoplasm. The Chloroplasts might be moving along with the
cytoplasm. Let Mr. D know if you do not see them moving. This is
called cytoplasmic streaming.
5. Focus up and down through the leaf. As you slowly move the focal plane
through the leaf count the number of cell layers that come into clear
focus.
6. Draw and label the Elodea cells in the analysis section and answer
questions 15 through 20.
F.
BACKGROUND INFORMATION FOR PARTS F AND G : Plastids are
cellular organelles of certain Eukaryotes where food or pigments are
made and stored. Chloroplasts are a type of plastid in which the
pigment chlorophyll is stored. For sections F and G you will examine
two other types of plastids: amyloplasts and chromoplasts
POTATO CELL: (one drawing)
1. Using a razor blade cut a section of potato as thin as possible.
CAUTION: Cutting edges can cause serious injuries. Always cut away
from yourself and others. Immediately return the razor blade when
you are done with it.
2. Place the thin section of potato on a slide.
3. Add several drops of water and place on a cover slip.
4. Examine under low. Center the thinnest par to f your potato section
in the field of view.
5. Examine under medium and high power and select the one that gives
you the best view of your potato cells.
6. Turn the Fine Adjustment back and forth rapidly while looking
through the ocular in order to get a better idea of what the cells look
like.
7. Stain the potato slice with iodine stain using the technique
described above.
8. Return the slide to the stage and view it under medium or high
power.
9. Draw the stained potato cell in the space provided. Each
intensely stained structure is called an AMYLOPLAST. Label your
drawing.
10. Answer questions 21 through 24.
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G.
RED BELL PEPPER CELLS: (one drawing)
1. Using a razor blade cut a small section of Red Pepper. CAUTION:
Cutting edges can cause serious injuries. Always cut away
from yourself and others. Immediately return the razor blade
when you are done with it.
2. Remove the outer skin layer and place the section on a wet mount
slide with a cover slip. You will need a piece about the diameter of a
pencil.
3. Examine under low and high power.
4. Turn the Fine Adjustment back and forth rapidly while looking
through the ocular in order to get a better idea of what the cells look
like.
5. Draw and label the bell pepper cell under high power in the space
provided. Be sure to note the tiny red colored plastids called
CHROMOPLASTS.
6. Answer questions 25 through 27.
EUKARYOTIC ANIMAL CELLS
H. CHEEK CELLS: (two drawings)
1. The cells that line the inside of your cheek are called epithelial cells.
They are constantly being soughed off like the cells of the outer skin.
As a result, some of these cells can be easily and painlessly removed.
2. Put a drop of water on a clean dry slide.
3. To collect some epithelial cheek cells gently scrape the inside of one of
your cheeks with the flat end of a toothpick using an up and down
motion.
4. Transfer your cheek cells from the end of the toothpick by swirling the
end in the drop of water on the slide. Do not spread the water drop
around the slide. Swirl ten or fifteen times.
5. Add a cover slip and view under low & high power. The cells will look like
small transparent baggies. The cells tend to clump together so try to
locate one by itself for clear viewing. Note their shape. Draw the
unstained cheek cells under high power in the analysis section.
6. Remove the slide from the stage for staining. Place a drop of iodine
stain at one edge of the coverslip. Draw the stain under the coverslip
with piece of paper towel at the opposite edge as done above.
7. View under low power. Find one cell and center it in your field of view.
Now switch to high power.
8. Draw the cheek cell under high power in the analysis section and
answer questions 28 through 30.
QUESTIONS: Answer the following questions on a separate sheet of paper
and staple it to the Student Report Page.
A. Cork cells:
1. What difference did you notice about the view of the cells near the edge of your
slice compared to the cells near the center of your slice? Explain!
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2. What cell structures are apparent when looking at cork cells?
3. Why do the cork cells appear to be empty?
B. Lactobacillus cells:
4. Describe the movement of lactobacillus cells.
C.
Oscillatoria and Gloeocapsa
5. What are some similarities of these two types of cells?
6. What does it mean to oscillate?
7. How did Oscillatoria get its name?
8. Did you add chloroplasts to your drawing of these cells? Explain your answer.
D. Onion cells:
9. What did you see through the microscopic that shows that onion is a plant?
10. What structures can be seen in an unstained onion cell?
11. What is differences do you see in the stained and unstained onion cells?
12. Do the onion cells that you examined in this lab have chloroplasts? Why or why
not?
13. Which cell in this organism has chloroplasts? Explain your answer.
14. Of all the cells in part A – D above which ones are prokaryotes?
E. Elodea cells:
15. What structures did you see in both Elodea cells and onion cells?
16. What are the differences between Elodea and onion cells?
17. What is the function of a cell wall?
18. How many chloroplasts are in an average Elodea cell? (Count 3 cells calculate the
average.)
19. Describe cytoplasmic streaming in Elodea cells. What might be the function of
cytoplasmic streaming in these cells?
20. How many cell layers are in an Elodea leaf?
F. Potato cells:
21. Why did the iodine turn color?
22. What is the name of the cell organelle that changed color with the iodine?
23. What is the function of this structure in the potato cell?
24. Why are potatoes a good source of carbohydrates?
G. Red Bell Pepper cells:
25. How are the red bell pepper cells different than the Elodea cells?
26. How are the red bell pepper cells similar to potato cells?
27. What structure is visible in the bell pepper cell that has not been seen in any
other cells during this lab?
H. Cheek cells:
28. What is different about the unstained and stained cheek cells?
29. How are cheek cells different from the plant cells you have studied?
30. What is the purpose of staining cells?
CONTINUE!
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31.
Complete the chart found at the end of the Student Report Page.
IDENTIFY THE STRUCTURES.
A
QUESTIONS 32 THROUGH 38.
B
C
34
35
D
E
36
Nuclear
Pores
ANSWER ON YOUR STUDENT REPORT PACKET.
32.
33.
34.
35.
36.
37.
38.
Name
Name
Name
Name
Name
Name
Name
the cellular structure shown in diagram A.
the large bean-shaped structure found in image B.
the structure that is seen as parallel lines at the top of image C.
the large organelle seen in image C.
the structure found at the number 3 in image D.
the darkest structure found in the middle bottom of image E.
the large round structure that takes up most of image E.
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