Procedures:
Mitosis in Onion Root Tips
Mitosis in plants occurs in localized areas known as meristems. The tip of the shoot and tip of the
roots are two of the areas where meristems occur. The root tip is covered with a protective sheath,
the root cap. The meristem is several layers of cells away from the tip of the root cap.
Materials
Used by permission from http://www.microscopy-uk.org.uk/micropolitan/botany/frame4.html
Examine the root tip slide photograph taken with the 4X lens.
Used by permission from https://molgen.osu.edu/
Question: Can you distinguish any cells?
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Are some cells longer than others?
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Looking near the root tip (but not at the root cap) can you see any cells in the process of cell
division? _____________
Used by permission from https://molgen.osu.edu/
8. Identify as many of the stages of mitosis as
you can. Make a sketch of a representative cell in each of the four stages of mitosis in the space
provided on your lab report form.
9. Go to http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html and complete
their online activity. Complete the chart in your lab report form as you go.
If you were to assume that the number of cells in a phase indicates the time spent during mitosis of
that phase, then you could infer that the phase with the largest numbers of cells would take longer
and that the phases with the fewest numbers of cells would be fastest. Time spent in a phase could
then be calculated, because it is known that the time for a typical onion cell to complete mitosis is 16
hours (960 minutes), from interphase to interphase. We can calculate the percentage of cells in each
phase by dividing the number of cells in a phase by the total number of cells counted.
Example: If your table indicates that 8 out of the 36 total cells observed were in anaphase, then
8/36 = .22
.22 x100 = 22 %
of cells are in anaphase. Calculate the amount of time spent in each phase of the cell cycle from the
percent of cells in that stage. (Multiply percentage of time in phase times the number of minutes in
the cell cycle).
Example:
22 % x 960
.22 x 960= 211. 2
211.2 minutes spent in anaphase.
10. Use http://nces.ed.gov/nceskids/createagraph/ or Excel to create a pie graph of number of
minutes spent in each cycle. If you cannot use either program, you may draw the graph.
Mitosis in Animal Cells
Telophase and
Cytokinesis
Whitefish is a
commonly employed organism for
study of animal mitosis.
Interphase
Prophase
Metaphase
Anaphase
Telophase
Telophase and Cytokinesis
Whitefish is a commonly employed
organism for study of animal
mitosis.
Materials
Photographs of prepared slides of whitefish blastula mitosis:
http://biog-1101-1104.bio.cornell.edu/BioG101_104/tutorials/cell_division/wf_review_fs.html
1. Examine the photographs of
whitefish mitosis and observe the
sliced blastula (discs) of Ascaris and
sketch cells in each stage of mitosis
in the space below.
Question: Summarize the
differences between mitosis in
plants and animals.
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Modeling the Stages of Mitosis
*Note: This section is highly
recommended, but not
mandatory.
Often, modeling can help us break a
process down into essential
components and sequences. Mitosis
is one such process. We will use a
set of pop beads to simulate the
appearance of a cell as it
progresses through the stages of
mitosis. Before beginning this part of
the lab, view an animation of
mitosis.
Materials
• Pop Beads, red and yellow
• 4 rubber stoppers (approx. 1 inch dia.)
• Yarn (Red and Yellow)
• Small Beads
• White string
1. After viewing the animation of
mitosis, you will use the pop beads
to examine the events and phases
of mitosis.
2. Obtain:
• 20 red beads and 20 yellow beads
• 8 rubber-tipped magnets
• 2 feet of red yarn and 1 foot of
yellow yarn (you may have to
cut this yourself)
• 4 of the cylindrical beads
• 2 3-inch short pieces of red yarn
• 2 3-inch short pieces of yellow
yarn
• 2 10-inch long pieces of red yarn
• 2 10-inch long pieces of yellow
yarn
• 2-3 feet of white string (you may
have to cut this yourself)
3. Assemble four “chromosomes” as
follows:
a. Place one red
bead in each end of a rubber-tipped
magnet
b. Place one yellow
bead in each end of a rubber-tipped
magnet
c. Place 5 red
beads in each end of a rubbertipped magnet
d. Place 5
yellow beads in each end of a
rubber-tipped magnet
4. Arrange the 2-foot long piece of
red yarn into a circle and place it on
your lab bench.
5. Arrange the 1-foot long piece of
yellow yarn into a circle and place it
inside the red yarn circle already on
the table.
6. Place one each of the short
yellow, short red, long yellow, and
long red pieces of yarn on the table
inside the yellow yarn circle.
7. Place the rubber stopper inside
the red yarn circle.
8. Place two of
the cylindrical beads inside the red
circle (but just outside the yellow
circle)
Question: What do each of the
pieces on the table before you
represent in a real cell?
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9. Simulate the events of prophase
by adding or removing material from
the yarn circles on your desktop.
Draw the cell as it appears in
prophase in the space below:
10. Simulate the events of
metaphase. Draw the cell as it
appears in metaphase in the space
below:
11. Simulate the events of
anaphase. Draw the cell as it
appears in anaphase in the space
below:
12. Simulate the events of
telophase. Draw the cell as it
appears in telophase in the space
below: