CYTOLOGY   

Lab Objectives:

Students should be able to...

  1. identify the various cell organelles either from a model or in the field of view of the microscope

  2. define the basic function of each cell organelle

  3. describe technique for creating a wet mount slide

  4. define the three type of tonicities and the effects each tonicity has on a cell

  5. identify the various stages and phases of mitosis


I. Cell  Model:  Learn and identify on a cell model the following cellular regions and various organelles. Cell Model 1, Cell Model 2

Plasma membrane (cell membrane) phospholipid bi-layer that surrounds the cell and controls movement of particles into and out of the cell
Cytoplasm fluid component in which the organelles are suspended
Nucleus control center of the cell and contains genetic material (DNA/RNA)
Nucleolus site of rapid RNA production
Endoplasmic Reticulum (ER) rough ER - site of protein synthesis

smooth ER - site lipid and carbohydrate synthesis

Ribosomes non-membranous organelle located within the rough ER and is the actual site of protein synthesis
Golgi apparatus (body) processing, packaging, and distribution of substances made by the ER
Mitochondria site of ATP synthesis
Lysosomes vesicle that contains hydrolytic enzymes
Centrioles (Centrosome) non-membranous organelle that forms mitotic spindle fibers
Vesicles (vacuole) liquid-filled sac used for storage of various organic and inorganic compounds


II. Cheek cell preparation: be able to recognize each of the cell structures apparent on a wet mount of cheek cells.

            1. Prepare your own slide by gently scraping your own inner cheek lining with a toothpick or wooden applicator stick.

            2. Smear the moist substance in the center of a clean glass microscope slide.

            3. Flood the smear with 1 drop of the methylene blue stain provided.

            4. Gentle place a coverslip on top of the stain.

            8. Place on the stage platform.

            9. Observe with the microscope, beginning with the scanning power.

            10.Recognize structures evident in the cheek cell preparation:  Picture

                     a. nucleus/nuclear membrane
                     b. cytoplasm
                     c. cell membrane
                     d. food debris and/or bacteria
            11.Dispose of the slide in a container of chlorine-based bleach as indicated by the instructor or by placing the slide into a glass disposal box.

 
III.  Cell physiology demonstration:   

A.  Osmosis and diffusion:

The instructor will demonstrate by video-micrograph the response of fresh, living red blood cells to solutions of various concentrations.

           1.  Pay attention to the instructor's comments about the use of fresh blood in an educational setting.
           2.  Predict results of osmosis in solutions of different concentrations. Picture
                  a. isotonic (same solute concentration as cell contents): no visible change in the cell
                  b. hypotonic (less solute concentration than cell contents): water gain resulting in swelling and potentially lysis of cell (hemolysis)
                  c. hypertonic (more solute concentration than cell contents): water loss resulting in crenation

B.  Mitosis:   

        Study prepared slides from the whitefish blastula in order to become familiar with a typical cell during its reproductive process.  The term "blastula" refers to a sphere of rapidly dividing embryonic cells. The whitefish produces good examples of cells undergoing mitosis, as they are large and easy to obtain and manipulate.  You will be given a slide which has about 30 pink dots on it visible to your unaided eye.  Each one of those pink dots, upon examination with the microscope, will show 20-50 cells.  These cells are stained with a dye which causes the cytoplasm to appear pink and nuclear material to appear purple.  Since each dot represents a slice through a 3-dimensional sphere of cells (the blastula), each cell will not be sliced directly through its axis.  Many cells will not show a recognizable structure.  Ignore those.  Scan around for cells which are cut in such a way that typical mitotic figures (appearances of typical stages of the process) are evident.  Use the photomicrographs in your text, your lab atlas, or attached as links to let you know what to look for.  

            1. Recognize various stages of the cell cycle:

 

Microscope Models
Interphase Interphase

Mitosis

Mitosis

            2. Recognize significant structures associated with the process of mitosis:

 

IV.  Useful Websites