Download The Human Cheek Cell

Name
Date
Period
Purpose: To view animal and plant cells and distinguish between them. This lab provides the opportunity to
view living cells and identify the parts of a cell that you have only seen in diagrams up to the point.
You will be working in a group of 4. Two members of the group will complete procedure part A while the other
members of the group will complete part B. Then you will switch microscopes when you are finished with your
drawings.
Procedure:
Part A: Cheek Cells
1) Put one drop of crystal violet on a slide. Caution: crystal violet will stain clothes and skin.
2) Gently scrape the inside of your cheek with the flat side of a toothpick. Scrape lightly.
3) Stir the end of the toothpick into the stain and throw the toothpick away.
4) Place a coverslip onto the slide (refer to microscope notes for proper coverslip placement)
5) Use the SCANNING objective to focus. You probably will not see the cells at this power.
6) Switch to low power. Cells should be visible, but they will be small and look like nearly clear purplish blobs.
If you are looking at something dark purple, it is not a cell.
7) Once you think you have located a cell, switch to high power and refocus.(Remember, do NOT use the
coarse adjustment knob at this point)
Sketch the cell at low and high power. Label the nucleus, cytoplasm, and cell membrane. Draw your cells
exactly how they look in the microscope. Before you start drawing, check with a teacher to make sure you
are view cells and not some other material.
Low Power
High Power
1) Why is crystal violet necessary?
2) The light microscope used in the lab is not powerful enough to view other organelles in the cheek cell.
What parts of the cell were visible?
3) List 2 organelles that were NOT visible but should have been in the cheek cell.
4) Is the cheek cell a eukaryote or prokaryote? How do you know?
5) The mouth is the first site of chemical digestion in a human and your saliva starts the process of breaking
down the food you eat. Keeping this in mind, what organelle do you think would be numerous inside the
cells of your mouth?
Part B: Onion Cell
1) Use your fingernail to scrape off a very small piece of onion. Make sure the piece is very thin. If it is too
thick then you will not be able to focus your microscope. Place it on the slide. Put one drop of crystal violet
on the onion and then place a cover slip on top.
2) Use the SCANNING objective to focus. You will see what looks like a very small brick wall.
3) Switch to low power. Cells should be visible, they will be tightly packed together.
4) Once you think you have located a cell, switch to high power and refocus.(Remember, do NOT use the
coarse adjustment knob at this point)
Sketch what you see and label the cell wall/membrane, and nucleus. Before you start drawing have a
teacher check to make sure that you are drawing a correct image.
Low
Med Power
1) Compare and contrast the plant and animal cells. Name 2 things that are the same and two things that are
different about them.
2) In terms of cell structure, why is it harder to see the outlines of the cheek cells than the onion cells?
3) Is the nucleus always in the center of the cell? Based on the other cell structures you know, why do you
think that is?
4) What are the differences in shape between the two types of cells? What causes this difference?
5) What is the relationship between plant cell structure and the ability of plants to stand upright without
bones?