Cell Observations Lab/Edwards-Knox Central School

Instructor: Mr. Buckley

Student Name -- ____________________

 

[Problem]

 

In a previous laboratory experience you learned how to use the microscope and make wet mounts.  In this lab activity you will prepare two different wet mounts and observe some animal cell slides. 

 

Materials needed:  microscope, two glass slides, iodine stain (Lugol's solution),

                                   methylene blue stain, two cover slips, an onion, and a toothpick

 

PART ONE:  Onion cell wet mount

 

[Procedure]

 

1.  Peel a translucent piece of tissue from the onion. (The smaller the piece the better.)

     Translucent means that you can see light through the specimen, but it is not transparent.

2.  Place the piece of onion on a glass slide and add a drop or two of the Lugol's solution.

     (Lugol's solution or iodine is a specific stain for plants.)  Cover the slide with a cover slip

     using your best wet mount making techniques.


3.  Observe the onion cell under both low and high power.  Make a drawing of one onion cell, using
     a pencil, labeling all of its parts as you observe them.   (At minimum you should observe the nucleus, 
     cell wall, and cytoplasm.)

 

Data:  Onion Cell Drawing (any power but preferably high power)


PART TWO:  Cheek cell wet mount

 

[Procedure]

 

1.  To view cheek cells, gently scrape the inside lining of your cheek with a toothpick.  DO NOT

     GOUGE THE INSIDE OF YOUR CHEEK!  (We will observe blood cells in a future lab!!  )


2.  Gently tap the toothpick onto the center of a glass slide.  Some of the cheek cells should

     fall onto the slide.


3.  Add a drop of methylene blue stain (specific for animals) and cover with a cover slip.


4.  Observe the cheek cells under both low and high power of your microscope.  Draw a diagram of one

    cheek cell, using a pencil, and label its parts.  (At minimum you should observe the cell membrane, 
    nucleus, and cytoplasm.)

 

 

Data:  Cheek Cell Drawing (any power but preferably high power)

                                      

 

[Conclusion  Questions]  You may need to research some of these using your notebook or textbooks.
 

I.              Complete the following chart

Cell organelle   Found in plant, animal, or both   Function of the Organelle or Structure
nucleus    
cell wall    
chloroplast    
cell membrane    
cytoplasm    

 

                              

II.    Why do we stain specimens?

 

III.   Why must the specimen you observe be very thin?

 

IV.   Onion cells are plants.  Therefore, why were there no chloroplasts in the onion cells you observed? 

 

V.    Centrioles might be observed in some of these cells with an electron microscope.  In which cells would 
        these be observed and what is the function of these cell organelles?
 

VI. What is the general shape of a typical plant cell? …of a typical animal cell?

 

VII. Inside the mouth, these cells are joined together in a sheet. Why are they scattered on your slide?