Download Name - Humble ISD

CELL LAB
Objectives:
1. To develop expertise using the compound light microscope
2. To develop expertise in making wet mount slides
3. To practice making scientifically accurate, correctly labeled microscopic drawings
4. To distinguish between plant and animal cells
5. To compare and contrast different types of specialized cells.
6. To observe plasmolysis in a plant cell.
Scientific Drawings:
Although it is not necessary to be artistic to make good biological drawings, you do need to be accurate and invest the time needed to do a
good job.
1. Obtain a plain, white sheet of paper. You will be using the paper in a landscape orientation.
2. Divide the paper into quadrants. Label as directed.
4. Use the plastic cup provided to draw a circle slightly off-center in each section. This circle represents your field
of vision when looking through the microscope.
5. The following criteria must be followed for all microscope drawings:
 Each drawing must have a descriptive title. In this lab, the title is the cell type/organism each drawing
represents. The title is written above the drawing.
 Below each drawing, indicate the magnification power used for viewing, sketching the specimen.
 All drawings must be done in pencil.
 Coloring must be done with colored pencils . . . no markers! Always choose a color that most closely
represents the color seen under the microscope unless specifically directed otherwise.
 All labeling is done to the right of the drawing. Use a ruler to connect the appropriate structure to the label.
Don not cross over lines.
 Six to eight cells provide an acceptable representation of the view.
Materials
Microscope
Water
Glass slides
Coverslips
Iodine
Methylene Blue
Janus Green
Red apple
Elodea
15% NaCl
Onion
Procedure
Elodea Leaf Cells
 Remove a young leaf. Place it in a drop of iodine and add a coverslip.
 Examine under low and high power.
 Using the high power objective lens, draw the plant cells.
 Try to observe cytoplasmic streaming. What creates this?
 Count chloroplasts in four different cells. Find the average. Record.
 Label the cell wall, chloroplasts, nucleus, and cytosol.
Red Pepper Cells
 Add a drop of water to a slide.
 Slice a very thin section of the red pepper skin.
 Add a coverslip.
 Observe under high power and low power.
 Locate the chromoplasts, plastids that store pigment molecules. How does the function of chromoplasts differ from
the function of amyloplasts found in potatoes?
 Sketch the cells.
 Label the cell wall, chromoplasts
Human Epithelial Cells Stained with Methylene Blue
 Add a drop of Methylene Blue stain to a clean slide.
 Gently scrape the inside of your cheek with a toothpick. Stir the scraping into the Methylene Blue. Put the used
toothpick in the trash!
 Add a coverslip.
 Locate a cluster of epithelial cells on low power. Examine on high power.
 Sketch the cells.
 Label the cell membrane, cytosol, nucleus, nuclear envelope.
Human Epithelial Cells Stained with Janus Green
 Add a drop of Janus Green stain to a clean slide.
 Gently scrape the inside of your cheek with a toothpick. Stir the scraping into the stain. Put the used toothpick in the
trash!
 Add a coverslip.
 Locate a cluster of epithelial cells on low power. Examine on high power. Janus Green stains the mitochondria
blue . . . the stain will fade after a few minutes so draw quickly!
 Label the cell membrane, cytosol, mitochondria, nucleus.
Observing Plasmolysis in Plant Cells
 Onion Cells
 Prepare a wet mount of a small piece of the epidermis of an onion. Observe under low power.
 Sketch and label the cells.
 Add 2 or 3 drops of 15% NaCl to one edge of the coverslip. Draw the salt solution across the slide by touching
a piece of paper towel to the fluid under the opposite edge of the coverslip.
 Sketch the onion cells.
 Label the cell wall, cell membrane.
 Apple Cells
 Place a drop of water on the slide.
 Obtain a piece of apple with the peel intact. Firmly hold the apple piece with one hand and a sharp razor blade
between the thumb and index finger of the other hand.
 Draw the blade across the surface of the peel tangentially so as to obtain very thin, almost transparent
sections. Pull the blade lengthwise during the cutting motion so as to use as much of the blade surface as
possible. Drop the sections into the drop of water. Use different locations on the peel surface to obtain
several sections. This may take some practice!!
 When you have several promising specimens, add the coverslip. Observe under low power . . . look for intact
cells around the perimeter of the specimen.
 Sketch and label the cells.
 Now add 15% NaCl using the procedure described above. You should be able to see plasmolysis of the cell
membrane and the tonoplast.
 Sketch the cells.
 Label the cell wall, vacuole with anthocyanin pigment, tonoplast, cell membrane, cytosol.