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CYTOLOGY
Cell Model: Learn and identify on a cell model the following cellular
regions and
various organelles.
Cellular Regions: Nucleus, plasma membrane and cytoplasm
Organelles: ribosomes, rough and smooth endoplasmic
reticulum, golgi
apparatus, lysosomes, mitochondria, centrioles,
nucleolus
Cheek cell preparation:
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. Let this smear air-dry.
4. Flood the smear with 2-3 drops of the methylene blue stain
provided.
5. Let the stain remain on the smear for two minutes.
6. Gently rinse the smear off with tap water.
7. Gently blot with a paper towel or bibulous paper (don't rub it!).
8. Place on the stage platform.
9. Observe with the microscope, beginning with the lowest power.
10. Recognize structures evident in the cheek cell preparation:
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.
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NOTE: For the lab practical, be able to recognize each of the cell
structures apparent on
the cheek cell preparation.
Cell physiology demonstration:
The instructor will demonstrate by video-micrography 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.
a. isotonic (same concentration as cell contents): no
visible change
b. hypotonic (less concentration than cell contents):
water gain resulting in
lysis of cell--in this case,
hemolysis
c. hypertonic (more concentration than cell contents):
water loss resulting in
crenation
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 and/or your lab atlas to let you know what to
look for.
1. Recognize various stages of the cell cycle
2. Recognize significant structures.
a. spindle apparatus
b. chromosomes
c. poles
d. equator
