Examining Plant and Animal Cells

Purpose: To examine the basic structure of a plant and animal cell.

Materials:

Per person

2 glass slides

2 slide covers

1 toothpick

Per table:

Microscope (2)

Paper towel pieces

Methylene Blue Stain

Iodine Stain

Paper towels

Petri dishes for drawing circles.

Safety: Wear aprons due to use of stains. Gloves are optional

Hypothesis: What do you expect to see (structurally) when you look at your cheek cell and an onion cell under the microscope?

Procedure:

Part 1 – Cheek cells (animal)

  1. Gently scrape the inside of your cheek with a toothpick. You may not be able to see anything on the toothpick but cells are there.
  2. Place one drop of water on a slide and mix the scrapings with the drop of water. Cover the mixture with a cover slip. Observe in low power but do not draw. Can you see the cells? Take the slide off the microscope.
  3. Place a drop of methylene blue stain near the edge of the cover slip and place a small piece of paper towel to the opposite edge of the cover slip – this will draw the stain under the cover slip and stain the cells.
  4. DRAW several cells and LABEL the organelles that you can identify. Use either low, medium or high power to get the best view. Remember to title your drawing and include your total magnification.

Part II Onion Cells (plant)

  1. Remove a thin piece of onion epidermal tissue from the inner surface of the onion.
  2. Place one drop of water on a slide and place the onion skin flat in the water. Cover with a cover slip. Observe in low power but do not draw.
  3. Take the slide off the microscope and place a drop of iodine stain near the edge of the cover slip using a piece of paper towel.
  4. DRAW several cells and LABEL the organelles that you can identify. Use either low, medium or high power to get the best view.

Observations and Analysis Questions - In lab notebooks in complete sentences

  1. What is the general shape of the onion cells? The cheek cells?
  2. Explain why you stained the cells?
  3. When staining the cells, which part of the cell stains darker than the other parts?
  4. Based on your drawings, which type of cell is larger, plant or animal? Explain your answer.
  5. What differences can you see between the animal and plant cells? What structures do they have in common? Give at least 2 for each.

Conclusion

Briefly summarize the experiment/restate the objective. Restate your hypothesis. Was your hypothesis supported or refuted? Why or why not? Include data in your explanation if applicable.