Name __________________-
Section_____
Date ____________
Virtual Mitosis Lab.
http://bio.rutgers.edu/~gb101/lab2_mitosis/index2.html
Mitosis is the sequence of events by which the nuclear material of one cell is distributed, by a
process involving chromosomes, into two equal parts.
At the right of the screen is a longitudinal section through an onion (Allium) root tip. The root tip
is responsible for the downward growth of the root and therefore, is one of the regions in the
plant where cells are actively dividing and elongating. Because of this, the root tip is an excellent
system in which to study the process of cell division (cytokinesis)and nuclear division
(mitosis) Furthermore, the chromosomes are fairly large and distinct, and this species has a
relatively small number of chromosomes.
Click: Begin Assignment
Part I Click on the root tip picture to magnify the image.
1. Find dividing cells in the onion root tip. What differences can you see when you compare
the nucleus of a dividing cell with that of a non-dividing cell? Use a few sentences and
illustrate with at least three different pictures of what you believe is a dividing cell and
two different cells that are NOT dividing.
Part II
1. Review the diagrammatic summary of cell division in your notes before you begin.
2. Then, view the video. You might want to watch it more than once. What the speaker is
saying is a “preview” of what is to come (he is ahead of the video). Notice that if the
screen is “frozen” at any one place, you could have a different “view” of the phase. Also
important to note is that division is a CONTINUOUS PROCESS.
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Name __________________-
Section_____
Date ____________
PART III. MITOSIS in PLANT CELLS
Now view the root tip. Click on a dividing cell and choose (at the bottom) which phase you
believe the cell to be in. Once you have correctly identified it, draw a picture of that cell in the
correct place on the chart (next page). Be sure to use the Onion Root tip sheet. Not all cells are
clickable. You will need to select an “appropriate” interphase cell.
PART IV. MITOSIS in ANIMAL CELLS - Ascaris
Slides of whitefish blastulae will be used to show mitosis and cell division in animal cells.
Although the result of these processes and many of the events are the same or very similar to that
of the plant cells, there are some differences. See what differences you can detect.
Click on any of the slides at the right to magnify (only some of the cells are “clickable”. Place
the cursor over a dividing cell and click once. Identify the stage of division.
Identify at least one cell in each stage. Draw each phase of mitosis and select an appropriate
interphase cell to draw.
PART III Time Spent in Stages of Mitosis.
Procedure
1. Go back to the onion root tip, and view an area that has approximately 50 cells (use 50 cells in the
SAME area). Record in which phase of the cell cycle each is in. If you find that some cells appear to
be between two phases, record these observations as well. Use the tables below to record your
observations.
2. For the Ascaris go to: http://www.3dham.com/animal/Mitosis-AscarisEggcs40x3.jpg
3.
Date Table
Onion Root tip
Ascaris (Fish Blastula)
Phase
Number of Cells
Interphase
Prophase
Metaphase
Anaphase
Telophase
2
Name __________________-
Interphase
Onion Root Tip
Section_____
Date ____________
Ascaris
Prophase
Metaphase
Anaphase
Telophase/Cytokinesis
3
Name __________________-
Section_____
Date ____________
Questions
1. Why is it more accurate to call mitosis “nuclear replication” rather than “cellular division”?
2. Explain why whitefish blastula and onion root tip are selected for study of mitosis.
3. What stage of the cell life cycle was predominant in most cells? Why is this so?
4. What evidence did you observe that indicated mitosis is a continuous process, not a series
of separate events?
5. If your observations had not been restricted to the area of an organism that is actively
dividing, how would your results have been different?
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Name __________________-
Section_____
Date ____________
Finally, go online and complete the activity on the following site:
http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/assignment.html
The assignment
In this activity, you will be presented with cells from the tip of an onion root. You will classify each cell
based on what phase it is in. At the end you will count up the cells found in each phase and use those
numbers to predict how much time a dividing cell spends in each phase. You can base your calculation
on a total cell cycle of 24 hours.
Copy this table onto a piece of paper. You can enter data in this table as you go along, or at the end of
the activity.
Interphase
Prophase
Metaphase
Anaphase
Telophase
Total
number of cells
36
percent of cells
100%
To complete this activity, scroll to the bottom of this page and click the “next” button
Notice there is a cell (it is in black and white). Look at the cell and determine what phase the cell
appears to be in. Click on the phase name where you believe this cell belongs. If you are incorrect, the
software will give you a clue and you will need to “retry”. Continue doing this until all cells are
“categorized”.
There are 36 total cells that you will evaluate. Determine what percentage is in each phase (remember
the percentages should sum to 100%, The percentage of cells is a reflection of how much time is spent
in each of the phases.
SUMMARY: Write a brief paragraph that summarizes the cell cycle, including interphase and the mphase. What did you learn about how much time is spent in each phase? Can you actually tell the
phases apart? Differentiate between the cells based on what you SAW (not on what you think you
should have seen).
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