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Mitosis Lab
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Materials
- Onion root (alium) slides
- Microscope
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Purpose
To observe the process of mitosis in action in onion (alium) root cells. To
gain a better understanding of the workings of mitosis.
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Predictions
The majority of the cells will be in interphase. Of the cells undergoing
mitosis, the majority will be in prophase, while very few will be in
metaphase, anaphase, and telophase.
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Procedure
View prepared onion (alium) root slides under a microscope. Diagram and describe
the five phases of mitosis:
- Interphase
- Prophase
- Metaphase
- Anaphase
- Telophase/Cytokinesis
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Data/Observations
For a description of each stage, just click on the image.
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Interphase
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 Prophase
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Metaphase
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Anaphase
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Telophase
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Stage of Mitosis |
Cells Counted |
Percentage |
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Interphase |
70 |
61 |
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Prophase |
28 |
24 |
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Metaphase |
2 |
2 |
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Anaphase |
5 |
4 |
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Telophase |
10 |
9 |
Most of the cells that we observed were in interphase (61%). Interphase is the longest stage of the cell cycle. Of the cells that were in mitosis, most were in prophase (24%). There were only a few cells in metaphase, anaphase, and telophase.
Excel charts can be seen by clicking on Cells Counted or Percentage here or in the table above.
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Analysis
From our experiment of counting the number of cells in various stages of
mitosis in an onion root tip, we found cells to be in
interphase 61% of the time. However, the text asserts
that "typically, interphase lasts for at least 90% of the total
time required for the cell cycle."
The cells we observed are specialized cells in that they exist only in
onion root-tips. Since they are at the tip of an onion root, more of
their time needs to be spent in mitosis so they can divide faster and the
root can grow faster. Therefore, since the main function of onion root-tip
cells is mitosis and not other cell activites, we believe that onion root
cells spend a smaller percent of the time they have for cell division
during interphase than most other cells.
We found that 24% of the cell's time was spent in prophase, 2% in
metaphase, 4% in anaphase, and 9% in telophase. This simply further
demonstrates our belief that the onion root-tip needs to go faster so it
spends more if it's time in mitosis than a normal cell.
Another explanation of the results we got could be because of the small
amount of sample information. With so little data, it could be
hard to get a good representation of real-life cells.
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Conclusion
Click on the links below to read our comparisons and contrasts of the
different phases in mitosis and meiosis.
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Mitosis/Meiosis |
| Compare |
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| Contrast |
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Error Analysis
During this procedure, there were many instances when we found
"gray areas" in terms of classifying the cell. Our greatest
challenge was to determine whether a cell was in interphase or
prophase. In some cases the nuclear membrane was still intact, but
the nucleoli had already disappeared. This can be
classified as neither prophase nor interphase, since the cell probably
was somewhere in between. So in cases like this, we may have made the
wrong choice.
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