Download The Human Cheek Cell

JBHA 9 Bio Cellular Structure
Name :___________________________
Date:______
http://www.youtube.com/watch?v=voS1W-vzOSU
Procedure:
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A. Prepare a wet mount slide of onion skin cells as
directed by your teacher.
You will be given a piece of onion.
Remove the thin, transparent membrane from the inner surface.
Place a flat piece of this membrane on a glass slide.
Cover the membrane with a drop of water and a cover glass.
Be careful to keep the membrane from folding and wrinkling.
Throw your left over piece of onion in the trash can.
B. Observe the slide with both low power and high power magnification.
: Plant Cells -- Onion
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Questions and Observations:
1. Is the membrane (skin) composed of one cell or many cells?
2. What is the general shape of these cells?
3. Make a sketch of a few cells as seen under high power. Draw and label all structures seen.
4. Estimate the length in microns of the cells, as seen under high power.
a) Count the number of cells, laid end to end necessary to cross the diameter of the field.
b) Divide the number of cells into the known field of diameter.
5. Do the cells have a cell wall?
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c.) Remove the cover slip, add a drop of methylene blue stain, and replace the cover glass on the
membrane.
d.)Observe the slide under both low and high power magnification,
6. Can you still see the double outer layer, that is, the cell wall?
7. Why was the stain added?
8. Can you see a dark, round structure inside the cell?
Do all the cells have the dark, round structure?
This structure is the control center of the cell called the nucleus.
9. Can you see more than one nucleus inside of the cell?
1 0. Can you see a lightly-stained, granular area within the cells? This area is called the cytoplasm.
11. Draw a few cells of the stained onion skin as seen under both low and high power. Label
structures
The Human Cheek Cell
1. List the 3 parts of the Cell Theory
_____________________________________
_____________________________________
_____________________________________
2. Describe or define each of the following
--cell membrane _____________________________
--cytoplasm _________________________________
--nucleus ___________________________________
Name ________________________________
Procedure:
1. Put a drop of methylene blue on a slide. Caution:
methylene blue 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 in the stain and throw
the toothpick away.
4. Place a coverslip onto the slide
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 very dark
purple, it is probably 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)
--organelle ________________________________
3. Sketch the cell at low and high power. Label the nucleus, cytoplasm, and cell membrane. Draw your cells to scale.
Low Power
High Power
5. Why is methylene blue necessary?
6. The light microscope used in the lab is not powerful enough to view other organelles in the cheek cell. Wha
parts of the cell were visible.
6. List 2 organelles that were NOT visible but should have been in the cheek cell.
7. Is the cheek cell a eukaryote or prokaryote? How do you know?
8. Keeping in mind that the mouth is the first site of chemical digestion in a human. 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?