Mitosis Lab
Purpose: To identify the most common and rarest stages of mitosis as well as the visible
characteristics of the five stages of mitosis in a plant cell.
 Hypotheses: Based on what occurrs during each step of mitosis (in our notes)
which stage is the fastest? slowest? (2 pts)
 Background- give me at least 3 differences between mitosis and meiosis.
Controls & Variables:
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Controls: onion root tip cells, maximum magnification for drawings
Independent Variables: different stages of mitosis
Response Variables: cell counts of the different stages.
Materials: Microscope, onion (Allium) root tip slides, lens paper and drawing paper.
Procedures: (summarize procedures or minus 3 pts)
1.
2.
3.
4.
5.
Review the four stages of mitosis from your notes, as well as interphase.
Obtain a prepared microscope slide of Allium root tip.
Clean your lens and the eyepiece with lens paper if necessary. Clean your slide and
stage opening with a paper towel if there is a lot of dust on your scope.
Examine the slide on scanning (40X) power and center the slide on the area of the root
shown below.
On low (100X) power locate several cells whose chromosomes are visible. The
chromosomes will appear in their various arrangements as indicated in the picture
shown below.
6.
Center, fine focus and switch to high (400X) power. Do not touch the gross
adjustment knob on high power.
7.
Search for cells in prophase, metaphase, anaphase and telophase. Create a data table
for the 4 stages and keep a running total of the number of cells you find in prophase,
metaphase, anaphase and telophase.
8.
Your total count for all 4 stages should add up to 50 cells, so you may need to move
your slide over to count another root tip.
9.
Create a bar graph comparing your count to the class average count. (4 pts)
10.
Answer questions 1-9.
Observations: (15 pts; 3 pts per drawing)
Locate and draw a cells in each phase of a CELL’S LIFE CYCLE (interphase, prophase,
metaphase, anaphase and telophase). Your drawings should be a maximum magnification for
your given scope. You should draw the cells of the required phase TO SCALE with all the
appropriate surrounding cells (at least 6 cells per drawing). Draw each of these cells in separate
circle (five drawings total). On the appropriate drawings label the: cell wall, nucleus, nucleolus,
spindle fibers and chromosomes. *hint: not all these labels are applicable for each stage of mitosis;
you have to play with the fine focus to see the spindle fibers.
Data Analysis (12 pts)
1.
On the slide what phase of MITOSIS seems to be the most common? What does this
mean about the length of time it is in this phase? (2 pts) Hint: interphase is not officially
a stage of mitosis!
2.
Which MITOTIC phase seems to be least common? What does this mean about the
length of time it is in this phase? (2 pts)
3.
What criteria (VISIBLE EVIDENCE) did you use to determine a cell was in
prophase?
4.
What criteria (VISIBLE EVIDENCE) did you use to determine a cell was in
metaphase?
5.
What criteria (VISIBLE EVIDENCE) did you use to determine a cell was in
anaphase?
6.
What criteria (VISIBLE EVIDENCE) did you use to determine a cell was in
telophase?
7.
During telophase or early cytokinesis how are the two new onion cells separated from
each other?
8.
In comparing the onion root with the animal models, list 2 differences between
mitosis in plants and animals. *Don’t say things like one has a cell wall while the other
doesn’t or the animal cell models are bigger or plant cells are green! (2 pts)
9.
Why did we use an onion root tip to make the prepared slide for this lab?
Conclusions (6 pts)
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Address your two hypotheses (4 pts).
Error analysis: if your count isn’t the same as the class’s average count explain why, but
don’t use personal mistakes as an explanation for the difference!
Suggestions