Unit 7 Lab 5: Plant Cells Name___________________________Date_________________Period____________ Introduction Although plant and animal cells share some common structures, plant cells have chloroplasts, cell walls, larger vacuoles and lack centrioles. However, some parts of plants may not have a particular organelle. Objectives: • • • •

Demonstrate the proper procedures used in correctly using the compound light microscope. Prepare and use a wet mount of living cells. Stain a wet mounted sample Identify cellular organelles in a stained tissue sample

Materials: • • • • • • •

Microscope Eyedropper 1 flat slide 1 cover slip Toothpick Onion cells Celery

• • • • • • •

Stain (Janis Green, Lugol’s solution) Sugar water solution in a beaker Paper towel Water Pencil Paper Eraser

Procedures

or

1. Before you begin, decide which cell type you will use for this lab (Onionskin or Celery) 2. To make a wet mount of celery tissue: a. Cut a section about ½ an inch long from a fresh piece of celery. b. Stand this section on end on a clean glass slide. c. Make a slice through the celery as close to the outer edge as possible. d. Put this thin sheet, inner side up, on the slide. Cut out the region from between two of the strands of celery. e. Add a drop of Janus Green B stain to the piece of celery and place a cover slip on the slide at the edge of the “wet” specimen at a 45-degree angle, and then carefully drop the cover slip onto the specimen minimizing “air bubbles.” f. Look at the cells under high power and make a drawing of one typical cell. 3. To make a wet mount of an onion’s skin: a. Obtain a thin piece of onionskin by taking an onion leaf and snapping it in two. b. Carefully remove the thin skin that will separate from the convex side of the onion leaf. c. Place the thin onionskin on a clean slide and a few drops of Lugol’s solution to stain it. Allow the stain to remain for a few minutes.

d. Place a cover slip on the slide at the edge of the “wet” specimen at a 45-degree angle, and then carefully drop the cover slip onto the specimen minimizing “air bubbles.” e. Compress gently and wipe any excess liquid with a paper towel. 4. View the plant specimen under Scanning, low and high power. Under high power, sketch a few cells of the plant specimen and label all visible components. Sketch the stained plant cell at scanning, low and high power. Label the plant cell’s organelles that you see. Draw your cells to scale and include the magnification. Scanning (______x)

Low (______x)

High (______x)

5. Rinse the cover slip and slide and discard the plant specimen. 6. The light microscope used in this lab is not powerful enough to view other organelles in the plant specimen. What parts of the cell were visible? What parts of the cell were not?

Parts of the cheek cell that were visible:

Parts of the cheek cell that were not visible:

7. How were the cells you observed different from the animal cells you observed in past labs?

Unit 7 Lab 6: Aquatic Plant Cells [Part I] Name___________________________Date_________________Period____________ Introduction Elodea is an aquatic green plant. You will notice structures that were not visible in the onion cell. The cell membrane is present; however, it is not visible as it is just inside the cell wall. In another laboratory exercise, you will have the opportunity to view the cell membrane of an Elodea cell. The most noticeable organelle will be the small circular chloroplasts. If you observe closely, and if the cells are fresh and alive, you might notice the movement of the chloroplasts around the periphery of each cell. This movement is called cyclosis and is the result of the movement of the cytoplasm (cytoplasm streaming). As cyclosis occurs, this helps the plant facilitate the transport of materials within the plant. Objectives: • • • •

Demonstrate the proper procedures used in correctly using the compound light microscope. Prepare and use a wet mount of living cells. Stain a wet mounted sample Identify cellular organelles and cyclosis in a unstained/stained tissue sample

Materials: • • • • • •

Microscope Eyedropper 1 flat slide 1 cover slip Toothpick Elodea

• • • • • • •

Stain (Lugol’s solution) Sugar water solution in a beaker Paper towel Water Pencil Paper Eraser

Procedures 1. Make a wet mount of a leaflet of Elodea. a. Place the small leaflet on a clean slide and cover with a cover slip. 2. View the Elodea cells under low and high power. 3. Under high power, sketch a small section of Elodea cells and label all visible components in the space provided on the backside of this sheet. 4. Look for the area of the central vacuole. Search for the nucleus, it is usually pressed against the cell wall as a faint gray color (use a drop of iodine to stain to enhance the nucleus). Notice the chloroplasts moving around the periphery of the cells. This is called cyclosis. 5. Discard the cover slip and leaflet. Rinse the slide and dry the slide. Replace the slide in the slide beaker

Sketch the Elodea cells at scanning, low and high power. Label the cell’s organelles that you see. Draw your cells to scale and include the magnification. Scanning (______x)

Low (______x)

High (______x)

Unit 8 Lab 6: Aquatic Plant Cells [Part II] Name___________________________Date_________________Period____________ Introduction Elodea is an aquatic green plant. You will notice structures that were not visible in the onion cell. The cell membrane is present; however, it is not visible as it is just inside the cell wall. In another laboratory exercise, you will have the opportunity to view the cell membrane of an Elodea cell. The most noticeable organelle will be the small circular chloroplasts. If you observe closely, and if the cells are fresh and alive, you might notice the movement of the chloroplasts around the periphery of each cell. This movement is called cyclosis and is the result of the movement of the cytoplasm (cytoplasm streaming). As cyclosis occurs, this helps the plant facilitate the transport of materials within the plant. Objectives: • • • •

Demonstrate the proper procedures used in correctly using the compound light microscope. Prepare and use a wet mount of living cells. Stain a wet mounted sample Identify cellular organelles and cyclosis in a unstained/stained tissue sample

Materials: • • • • • •

Microscope Eyedropper 1 flat slide 1 cover slip Toothpick Elodea

• • • • • •

Saline (hypertonic) solution Paper towel Water Pencil Paper Eraser

Procedures 1. 2. 3. 4. 5. 6.

Locate another piece of the aquarium plant Elodea (You can also use lettuce). Tear off one of the leaves, put the leaf on a glass slide Add a drop of aquarium water and a cover slip. Look at the slide under medium or high power, what do you notice about the cells? Obtain the bottle of hypertonic solution, a fairly concentrated solution of salt in water. Put a drop or two of the saline hypertonic solution next to the cover slip of the previously prepared slide. 7. Draw it under the slip with a piece of filter paper or paper towel. 8. Describe what happens to the flow of chloroplast within the cell as you add the saline hypertonic solution.