Name _____________________
Date ______________ Per. ____
Onion and Cheek Cell Lab
Purpose: In this lab, you will prepare and observe cells from both a plant (onion) and an animal (your own
cheek!).
Materials: Safety goggles, lab coat, microscope, this paper, slide, coverslip, toothpick, forceps, iodine stain or
food coloring, onion tissue, and your own cheek
Assignment: Your assignment is to prepare and observe a sampling of cheek cells and onion cells and sketch
them in the spaces provided on the back of this sheet. You are also required, on your sketch, to label any
visible part or organelles, under the correct magnification you used. Lastly, you need to write down any other
interesting observations (differences between cells, interesting things you saw/discovered, etc.) on the back
and complete the questions.
Procedure:
For the onion cell:
1. Get a slide and place a small amount of onion tissue in the center. To do this, snap a piece
of onion in half and gently peel away one layer. Use the forceps to get the layer as smooth
as possible on the slide. Try not to have any wrinkles in the onion skin.
2. Add a small drop of iodine stain or food color directly to the tissue. Careful! Iodine is not
toxic, but it will stain both your skin and your clothes.
3. Place a coverslip over the newly stained tissue. Be careful to not trap any air bubbles.
4. Put the slide on the microscope stage, making sure the microscope is on LOW POWER
(40X)!
5. Go through the 3 powers, focusing each time, (40X, then 100X, and then 400X) making
sketches, and writing down observations.
6. Be sure to label any organelles you see. You may be able to see: cell wall, cell membrane,
nuclei, and cytoplasm.
For the cheek cell:
1.
2.
3.
4.
5.
6.
Clean off your slide from above carefully so iodine does not splash.
Add a drop of iodine FIRST to the empty slide.
Using the blunt (not sharp) end of a toothpick, gently scrape the inside of your cheek.
Swirl the toothpick end (where the cheek cells are) in the iodine drop on the slide.
Place a coverslip on the stained cheek cells. Be careful to not trap any air bubbles.
Observe under the microscope following steps #4 – 6 for the onion cell above.
Don’t forget to clean up by cleaning and drying your slide and coverslip. Make sure any iodine is
cleaned up and microscope is turned off and back to lowest power. Now answer the questions on the
back.
Name _____________________
Date ______________ Per. ____
Write down any interesting observations you saw on either or both of the slides (differences between cells,
interesting things you saw/discovered, etc.).
1. Why is iodine/food coloring necessary in this lab?
2. What is the basic unit of life?
3. Where do all living things come from?
4. Where do other cells come from?
Sketch the cell at low, medium, and high power. Label the nucleus, cytoplasm, cell membrane, and cell
wall in the appropriate cells.
Onion Cells:
40X
100X
400X
Cheek Cells:
40X
100X
400X