Name ___________________________________________ Onion Root Tip Mitosis Lab
Growth in an organism is carefully controlled by regulating the cell cycle. In plants, the roots
continue to grow as they search for water and nutrients. These regions of growth are good for
studying the cell cycle because at any given time, you can find cells that are undergoing mitosis.
In order to examine cells in the tip of an onion root, a thin slice of the root is placed onto a
microscope slide and stained so the chromosomes will be visible. The cells you'll be looking at
in this activity were photographed with a light microsope and then digitized so you can cut
them out and organize them.
Although slicing the onion root captures many cells in different phases of the cell cycle, keep
in mind that the cell cycle is a continuous process. Scientists have divided the mitotic cell
cycle process into 6 phases, each characterized by important events.
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.
Attach the pictures to the correct phase of the cell cycle. Then count up the numbers in each
phase to determine the percentages. Then use the pie chart to show the percentage of cells in
each stage of the cell cycle.
Interphase Pictures:
Prophase Pictures:
Metaphase Pictures:
Anaphase Pictures:
Telophase and Cytokinesis Pictures:
Title of Chart: ___________________________________________________________
Interphase
Prophase
Metaphase
Anaphase
Telophase/Cytokinesis
Total
number of cells
36
percent of cells
100%
Title of Pie Chart: ________________________________________________________
Key:
Conclusion:
1.
What stage were the majority of cells in? ___________________________
2. Which stage is the longest stage of the mitotic cell cycle? ______________________
3. How does plant cell division differ from animal cell division?
4. How does plant cell division compare to animal cell division (similarities)?
5. Explain what the following statement means, “Mitotic Cell Cycle is a continuous process,
not a series of separate events.”