Part A. the Cell Wall

Cell Lab

Part A. The Cell Wall

Cork cells are excellent for studying a cell part common to all plant cells. That part is the cell wall. It is the only cell part remaining in a cork cell; therefore, it is easily visible.

Obtain a prepared slide of cork.

Examine the cork slide under scan and low power only. If you use high power you run the risk of breaking the slide. Be very careful. Use the fine adjustment to obtain a three-dimensional view of the cells.

Use the space below to draw several cork cells as they appear under the low magnification Label the cell wall.

1. What name is given to the small units making up cork and all living things? ______

2. Describe the appearance of these units in cork. ______

3. Are cork cells alive? ______

4. Are the cells filled with living material or are they empty? ______

5. What specific cell part is all that remains of the cell? ______

6. In 1665, Robert Hooke, an English scientist, reported an interesting observation while looking through his microscope at cork. “I took a good clear piece of cork, and with a penknife sharpened as keen as a razor, I cut a piece of it off, then examining it with a microscope, me thought I could perceive it to appear a little porous, much like a honeycomb, but that the pores were not regular.”

What were the honeycomb units at which Hooke was looking? ______
What specific cell part was all that was left of cork? ______
What carbohydrate makes up this part? ______
Are cork cells part of a producer or a consumer? ______

Part B. Cell Membrane and Cytoplasm

Human cheek cells are excellent for examining cell membranes (the outer covering) and cytoplasm (cell contents).

Place a drop of iodine solution onto a slide.

Gently scrape the inside of your cheek with the end of a toothpick. You will not be able to see anything on the toothpick when you remove it from your mouth.

Dip the toothpick into the iodine on the slide and mix once or twice.

Add a cover slip and examine under low and high power of your microscope.

Locate and examine cells that are separated from one another rather than those that are in clumps.

Use the space below to draw several cheek cells as they appear under high magnification

Label the cell membrane and cytoplasm.

1. Describe the shape of cheek cells. ______

2. Do cheek cells have cell walls? ______

3. Do cheek cells have cell membranes? ______

4. Why might the shape of cheek cells be less regular than the shape of cork cells? ______

______

5. Describe the appearance or texture of cytoplasm. ______

6. Are cheek cells alive? ______

7. Do cheek cells come from consumers or producers? ______

8. Why was iodine solution added to the cheek cells? ______

Part C. Cell Nucleus and Nucleolus

Onion bulb cells can be used to observe the cellular structures called the nucleus and nucleolus.

Remove the almost transparent layer of cells between the rings of the onion. Place this layer onto a microscope slide.

Add a drop of water to the slide. Uncurl or unfold any overlapped portion of the cell layer. Make sure the layer is perfectly flat. Add a cover slip.

Observe the cells under low and high power of your microscope. Note the brick wall appearance of the cells with cell walls separating the cells.

Attempt to locate a small round structure, the nucleus, within each cell.

Stain the cells with iodine stain.

Now locate a nucleus. Examine a nucleus carefully by using the three-dimensional technique.

With high power, observe the tiny dot or eye-like structures within the nucleus. These are nucleoli.

Diagram and in the space provided what you observe under high power. Label the cell nucleus and nucleolus

1. Is cytoplasm visible in onion cells? ______

2. Can you see the cell membrane? ______

3. How many nucleoli are in each nucleus? ______

4. Why were the cells stained? ______

5. Other than the nucleoplasm and nucleoli, what is found in a nucleus? ______

Why might you not be able to see these structures at this time? ______

6. What is believed to be the function of the nucleoli? ______

7. What structure separates the contents of the nucleus from the cytoplasm? ______

Part D. The Flower Petal

Prepare a wet mount of a small piece of flower petal. Observe under low and high power magnification.

Use the space below to draw several flower petal cells as they appear under high magnification.

1. Is a flower a producer or consumer? ______

2. Do petal cells have cell walls? ______

3. Do petal cells have cytoplasm? ______

Part E. Chloroplasts

Another organelle found in the cells of most producers is the green chloroplast. Elodea, a common

water plant, is good for observing these important structures.

Prepare a wet mount of an elodea leaflet.

Using low power of your microscope, position you slide so you are looking near the edge of the leaflet. Locate green, oblong cells. Examine these cells under high power.

Note the small green organelles inside each cell. These are chloroplasts. Movement of the chloroplast within the cell can often be observed. Attempt to locate moving chloroplasts.

Observing one cell for several minutes is sometimes needed in order to see cytoplasmic streaming (movement). Light from the scope will warm the cell and help to induce movement.

Now take your slide and stain the elodea with iodine stain. Locate a spike cell along the edge of the leaflet.

Label in the space below an oblong cell and a spike cell as seen under high power.

Draw what you see in the space provided.

Can you see nuclei in the spike cells? ______

2. In what part of a cell are chloroplasts embedded? ______

3. Do elodea cells contain nuclei? ______

4. Do elodea cells have cell walls? ______

5. What makes chloroplasts green? ______

6. An elodea leaf appears uniformly green to the eye. Is the green color distributed evenly throughout the cell or is it only in specific organelles? ______

7. Is elodea a producer or consumer? ______

8. What is the function or role of chloroplasts? ______

9. Term referring to the cell movement - ______

Organelle responsible for this movement - ______

10. In what direction is this movement? ______

Part F. Nongreen Plastids

Nongreen plastids that serve as food storage areas are visible in potato cells.

Use a razor blade to cut a very thin slice from a potato chunk. Do no use the peel. The slice must be tissue-paper thin.

Prepare a wet mount of the slice. Observe the potato cells under low and high power of your

microscope. The cell wall of individual cells may be observed. However, the contents of these cells will contain so many plastids that you will not be able to see any other organelles. (Reduced light will aid in observing the cell wall.)

Add iodine stain. Observe the cells under low and high power.

Diagram and in the space below several potato cells under high power. Label the leucoplasts.

1. Is potato a consumer or producer? ______

2. What might be the chemical nature of the substance in plastids? (Use the color after the addition of iodine as a clue.) ______

3. Are nongreen plastids capable of directly manufacturing the chemical substance found there? ___

4. Name of these plastids - ______

Function of this type of plastid - ______

Comparison of Producer and Consumer Cells

Cell Type / Cytoplasm / Nucleus / Cell Wall / Chloroplasts
Producer
Consumer

Summary

1. What cell parts are found only in cells of producers? ______

2. Nonliving covering of a plant cell - ______

3. What advantage do producer cells have over consumer cells because of the chloroplasts?

______

4. Why is it necessary for all cells to have a nucleus? ______

5. List at least three other organelles that are found in the cytoplasm of all cells.

1. ______

2. ______

3. ______

6. Complete the drawing. It shows a typical plant cell. Label those parts listed below.

cell wallcell membranenucleusendoplasmic reticulum

cytoplasmchloroplastnucleolusGolgi body

ribosomemitochondrionvacuole

7. Complete the drawing. It shows a typical animal cell. Label those parts listed below.

cell membranenucleusnucleolus endoplasmic reticulum mitochondrion centriole Golgi body

ribosomelysosomecytoplasm