Experiment: Plant Cells -- What Are the Parts of the Onion Skin Cell?

Procedure:

• 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.

MICRO LAB 4: Plant Cells -- Onion

Name :___________________________ Date:____________________________

• 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.

____________________________.X high power

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?

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.

Stained onion skin cells         Stained onion skin cells

______________X power(high)     _____________X power( low)