Cytologist______Date______

Are All Cells Alike?

Key Question: Are the structures and functions of cheek cells (animal cells) the same or different from those of onion cells (plant cells)?

Today you will work in pairs as cytologists to answer this question. You will be preparing wet mounts of both an onion cell and a cheek cell, observing your slides under the microscope and comparing and contrasting your observations. You will be recording your observations by making accurate sketches and will have to carefully label the parts of the cell that you can identify.

Assessment: Theskills listed in this table are worth 10 points each. Following the completion of the lab list next to each criterion how many points you think that you earned. Your answers to the discussion questions at the end of the lab will also be part of your assessment. Each question at the end of the lab is worth 4 points.

What I think I earned / What I earned / Skill
Recorded accurate, complete neat notes about structure and function of plant and animal cells
Followed lab safety rules.
Properly handled microscope
Worked cooperatively with my partner
Correctly followed procedure for preparing wet mount slides of a check and onion cell
Carefully drew what I observed
Completely answered questions so that I communicated that I understood important ideas

Procedure: Onion Cell

1. Place a thin onion skin piece onto the center of a slide. Add a drop of water and then a cover slip.

2. Carefully observe under low power. Record the power of magnification. Draw what you see in Figure 1.

4. Now remove the cover slip and add one or two drops of methylene blue. Add the cover slip. Switch to higher power. Record the power of magnification.

Draw what you see in Figure 2.

Label the following organelles: cell wall, cell membrane, nucleus, and cytoplasm. Figure 1:My Drawing of an Onion Skin Cell Figure 2: My Drawing of a Stained Onion Skin Cell

Power of magnificationPower of magnification

Low Power =______High Power = ______

5. Is an onion cell a plant or animal cell? ______

6. What is the shape of the onion cell?______

7. Does the outer boundary of the cell appear as a double or single line? ______

8. Name one part the plant cell has that the animal cell does not. Why does it have this part? What does it do? ______

______

Procedure: Cheek Cell

1. Place a small drop of methylene blue dye onto a clean slide.

2. Using a flat toothpick, gently and carefully scrape the inside of you cheek.

3. Place the toothpick tip into the dye and mix. The dye stains the cells so you

can see them. Immediately throw your toothpick away.

4. Place the slide under low power. Record the power of magnification. Carefully draw what you see in Figure 3.

5. Switch to high power. Record the power of magnification. Carefully draw what you see in Figure 4.

Label the nucleus, cell membrane, and cytoplasm. Draw a straight line from the cell part to its label.

Figure 3: My Drawing of a Cheek Cell Figure 4: My Drawing of a Cheek Cell

Under Low Power of Magnification ______Under HighPower of Magnification ______

Analysis:

  1. What is the shape of the cheek cells?

______

  1. Why did we add dye to our cheek cells? ______

3 . What is the dark round shape inside each cell? ______

4. Describe the way the cytoplasm looks. ______

5. Looking at the dark outline around the cheek cell, does this boundary appear as a single or double line?

______

6. What is the outer boundary around the cheek cell called? What is its function?______

7. Is your cheek cell an animal cell or plant cell? ______

8. As you adjusted the microscope to higher magnification, what happened to the number of cells that you could see in your field of view?

______

______

9. As you adjusted your microscope to higher magnification, what happened to the detail that you could see?

______

______

10. Count the number of cells that are seen in the field of view under low magnification and also under high magnification. Using a ratio, (L;H) compare the number of cells observed in each field of view.______

Conclusion: (After completing this investigation, I learned…______

______