Download Cell Types

BIOLOGY – Activity
Cell types
Period 1 2 3 4 5 6 7 8
Date: _____________
Station # _____
Names _____________________
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Introduction
There are many types and categories of cells. One of the major divisions of cell types is
between plant and animal. While these cells have many things in common, there are certain
specific structures that can easily distinguish them from each other. With the aid of a
microscope, it is possible to see these differences quite easily. The most easily obtained animal
cell is the human cheek cell. These cells are known as epithelial cells and line the inside of the
cheek where they can be scraped off with little effort since they fall off continuously anyway
and are replaced on a daily basis. Plant cells are also easily obtained but may or may not
contain chloroplasts depending on the part of the plant they come from. The leaves of the water
plant known as Elodea are ideal for seeing chloroplasts and do not have to be stained to see
cell parts since the chloroplasts are very green due to all the chlorophyll they contain.
Objective
To observe and identify some of the basic differences between plant and animal cells and to
gain practice in the art of staining temporary wet mounts
Materials
microscope
slides
cover slips
flat toothpicks
onion
Elodea
forceps
Lugol’s iodine
Methylene blue
pipette
Procedure ( part 1 )
1. Place a couple of drops of water in the center of a clean glass slide.
2. Gently rub the inside of one of your cheeks with the blunt end of a flat toothpick
using a gentle up and down motion. Do not use force since you are looking for cheek
cells and not red blood cells!
3. Remove the epithelial cells from the toothpick by swirling the end of the toothpick
gently in the drop of water on the slide. Dispose of the toothpick in the waste basket.
Lower a cover slip at an angle over the drop of water that should now contain cells so
that no water bubbles are present.
4. Place a single small drop of Methylene blue stain on the slide at the edge of
the cover slip. Tear off a small piece of paper towel and hold it at the edge of the cover
slip opposite the drop of stain. The paper towel should draw water from under
the cover slip and pull the stain from the opposite side of the cover slip under the cover
slip , thus staining the cells.
5. Examine the stained cheek cells with the microscope using the proper technique
to focus them on high power.
6. Draw a diagram of a single stained cheek cell as seen under high power. Label the
following parts: cell membrane, cytoplasm, nucleus. Draw your picture in the circle
provided and on the blanks to the right specify the type of cell and the power of
magnification at which it was viewed. When labeling parts, use straight, horizontal
lines to point to the part and print the name of the part at the end of the line. Color your
drawing to match the stain used.
Procedure ( part 2 )
1. Place a couple drops of water in the center of a clean glass slide.
2.
Use the forceps to carefully remove the epidermal layer from the inside curved
surface of a piece of onion and spread the piece out flat in the water on the slide.
3.
Place a drop of Lugol’s iodine solution directly in the onion tissue and add a
cover slip, trying to avoid any air bubbles.
4. Use proper technique to focus on a few cells on medium power.
5. In the circle provided, draw all that you see in the field of view and label the
following parts: cell wall, cell membrane, cytoplasm, nucleus. As before, indicate
the name of the specimen and the magnification. Use the proper color for contrast.
Procedure ( part 3 )
1. Obtain a small leaf from the tip of a sprig of the water plant Elodea.
2. Place the leaflet with its upper surface facing down on a clean glass slide and add
a drop of water and a cover slip.
3. Use the proper technique to focus on high power and draw all that you see in the
field of view. Label the cell wall, cell membrane, cytoplasm, and chloroplast and
indicate the specimen name and magnification.
Analysis
1. What are the functions of the following cell parts?
a. cell membrane ________________________________________________
b. cell wall _____________________________________________________
c. cytoplasm ____________________________________________________
d. nucleus ______________________________________________________
e. chloroplast ___________________________________________________
2. Describe the shape and appearance of a cheek cell __________________________
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3. Describe the shape and appearance of an Elodea cell. ________________________
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4. Which part of a plant cell gives it shape? _________________________________
5. Which part of an animal cell gives it shape? _______________________________
6. What cell structure did the Elodea have that the onion did not? ________________
7. Do all plant cells contain chloroplasts? Why or why not? _____________________
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8. What is the purpose of staining? _________________________________________
9. What cell structures(s) did you observe in the onion that provides evidence that
onions are plants? __________________________________________________
10. What cell structure(s) did you observe in Elodea that were not in the cheek cell?
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