Name: ____________________________________
Period ___
Page # ____
The Human Cheek Cell
A. Microscope: Review the compound microscope, label diagram, practice focusing.
B. Cheek cell wet-mount procedure: OBSERVE DEMONSTRATION CLOSELY!
1. Place a paper towel on your desk. All slide prep is done on this.
2. Put a drop of water on a slide and then one of methylene blue on top of the water. Caution: methylene
blue will stain clothes and skin.
3. Gently scrape the inside of your cheek with the flat side of a toothpick. Scrape lightly.
4. Stir the end of the toothpick in the water/stain and throw the toothpick away.
5. Place a coverslip onto the drop’s edge at a 90o angle. Tilt halfway down slowly, then let drop.
6. Place slide on stage (no clips!). Lower the nosepiece objective to its closest position to the slide.
7. With coarse adjustment, slowly begin to focus. Cells should be visible, but they will be small and look
like nearly clear blue or purplish blobs. If you are looking at something very dark, it is probably not a cell
8. Once you think you have located a cell, move slide gently until it is centered. Switch to high power
and refocus with fine adjustment. (Remember, do NOT use the coarse adjustment knob at this point…)
C. Sketch the cell at low and high power. Label the nucleus, cytoplasm, and cell
membrane of a single cell. Draw your cells to scale.
Low Power – 100x
High Power – 400x
1. Why is it necessary to use methylene blue?
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 actually be in the cheek cell.
4. Is the cheek cell a eukaryote or prokaryote? How do you know?
Use this key while finding the location of each component on your microscope:
Stage clips (do not generally use…)
Revolving Nosepiece
Objectives (4x, 10x, 40x)
Ocular Lens (Eyepiece – 10x)
Diaphragm
Stage
Fine Adjustment Knob (use last!)
Base
Coarse Adjustment Knob (use first!)
Body tube
Light Source
Arm