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Return to Model Zoom Lesson Plans |
 ZOOMplan
You...Instead of the Onion Skin
(ZOOMplan developed by Dr. Vickie Harry, Clarion, Pennsylvania) |
What structures can be observed in epithelial cells?
The epithelial cells, which form the outer layer of skin of animals
and also line certain body cavities, are flattened pancake-like
cells, arranged in sheets with no spaces between them. New cells are
constantly being formed under the layer, this replacing the surface
cells that are worn off. Cells performing the same function often
are similar in shape. Epithelial cells, whether from fish, frog,
bird, or human, look somewhat alike. The outer skin of frogs,
salamanders, or other animals can be examined under the microscope.
Small pieces of cast-off skin can be found floating in an aquarium
where aquatic animals are kept. There are similarities and
differences between plant and animal cells. Onion cells and human
cells differ in size and shape. The onion cells are thicker than the
flat animal skin cells. Both types of cells have a nucleus. The
onion cells have thick, nonliving cell walls (as do most plant
cells); the animal cells do not. Cell membranes are the living outer
boundaries of plant and animal cells. In plants, living membranes
are usually closely surrounded by cell walls and cannot be
distinguished easily under a microscope.
Science: Observational investigation of the structure of human epithelial cells
Objective:
Using DigiScope technology, MAIS elementary and middle school
students will observe their own epithelial cells from the inside
linings of their cheeks.
Concepts: Structure and function of
epithelial cellular organization in animals
Processes: Observing,
describing, identifying, communicating, predicting, measuring,
collecting data, recording data, displaying and interpreting data,
comparing data
Project AERO Standards: Science: # 1,5, a. Keep
records of investigations and observations and not alter the
records. Science: # 2, 5, c. Know how to make sketches or models to
aid in explaining scientific procedures or ideas. Science: # 16, 5,
a. Identify the cell as the fundamental unit of living organisms and
recognize that some organisms are unicellular, while others are multicellular.
Science: # 4, 5, a. Use technology, including
cameras, tape recorders, and computers, to store and retrieve verbal
and graphic information and data. b. Use a variety of scientific
tools to collect data. Math: # 7, 3, a. Estimate before measuring to
determine the reasonableness of a solution. b. Estimate and measure
length, time, temperature, and weight to the nearest unit using
customary, metric, and nonstandard measurement.
Materials: Flat
wooden toothpicks, epithelial cells from cheek linings, slides and
coverslips, Methylene Blue stain solution, droppers and water, paper
towels, DigiScopes
Procedure:
1. Using a dropper, place two drops of
water on a slide.
2. Collect human epithelial cells by gently
scraping the inside of your cheek with the wide end of a flat
toothpick. Touch the material collected on the toothpick to the
water on the slide.
3. Add a drop of Methylene Blue and cover with a
coverslip.
4. View the epithelial cells at different magnifications
to observe the detail of cellular structure.
5. Remove the eyepiece
from the DigiScope and insert the camera in its place. Now go to the
main menu of Motic Play and click the Capture button. Print the
image by clicking on the Jump to Edit button. When in the editing
window, click the Print button.
6. Use a strand of your hair to
measure the cells by placing a short piece of hair across the
epithelial cells. Predict how many widths of your hair you could lay
side by side over the length of one cell or the width of one
cell.
7. Compare the images of the plant cells from an onion skin to
the human epithelial cells. Compare the similarities and the
differences.
8. Locate and label the parts of the plant cells and the
animal (cheek) cells.
9. Prepare a slide with both onion cells and
epithelial cells on it. Students may want to make an illustrated
booklet for a PowerPoint presentation comparing the plant and
animals cells.
References:
AIMS Education Foundation. (1995).
Magnificent Microworld Adventures. Fresno, CA: AIMS Education Foundation.
K – 8 Experiment Manual. (2002). Dancing Cheek to Cheek.
Science Kit and Boreal Laboratories & Motic Incorporation Limited. |
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