Name: ________________________
Date: _______________ Pd: ____
Online Onion Root Tip Mitosis
Introduction:
In this activity, you will be presented with cells from the tip of an onion root. You will classify each cell
according to the phase it represents. At the end, you will count up the total 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.
Getting Started:
1. To start today’s lab you will need to go to the following website www.biology.arizona.edu
2. In the left Activities column under Cell Biology click on Onion Root Tips.
3. Answer the following questions based on the information given on the home page Online Onion
Root Tips.
Questions:
a. Why do scientists use root tips to study the cell cycle? ________________________________
____________________________________________________________________________
b. How do scientists prepare an onion cell for viewing under a microscope? _________________
____________________________________________________________________________
c. Although slicing the onion root captures many cells in different phases of the cell cycle, the
cell cycle is a _____________________ process.
d. How many phases are in the cell cycle? ____________
4. Click Next.
Fill in the blanks for the phases of the cell cycle.
a. Interphase:
 Cell is engaged in ______________ activity

________ duplicates in preparation for ________________

___________________ are not clearly visible

Dark spot called the __________________ is visible
b. Prophase:
 _______________ begins to condense and become ___________ as _________________

________________ _______________ dissolves
c. Metaphase:
 Spindle fibers align the ___________________ along the _____________ of the cell

This ensures that each new nucleus receives _____ copy of each _____________________
d. Anaphase:
 Paired _____________________ move to ______________________ sides of the cell
e. Telophase:
 New _________________ form around the __________________ nuclei

______________________ disperse and are no longer _________________ under a light
microscope
5. Click Next again
6. You should see a data table such as the one shown below. Click Next again.
7. This will bring you to the activity.
8. You will be shown a cell and you need to determine if it is in interphase or one of the phases of
mitosis. When you think you know what phase it is in click on that phase. If you are correct, the
cell will be placed there. If not, try again until you get it correct.
9. Once you have classified all the cells in the activity, complete the data table and answer the
following questions.
Data Table:
Interphase
Prophase
Metaphase
Anaphase
Telophase
Total
# of cells
36
% of cells
100%
To determine percent:
Number of Cells in Phase
Number of Total Cells
x 100
Analysis and Conclusion:
1. Create a graph comparing Interphase and the phases of mitosis and the number of cells in each
phase.
2. Create a pie graph comparing the percent of cells in Interphase and the phases of mitosis.
3. In what phase overall does the cell spend the longest time? ______________________________
Why do you think the cell spends most of its time in this phase? ___________________________
_______________________________________________________________________________
4. In what phase of mitosis does the cell spend the most time? ______________________________
5. Draw and label the identifying characteristics of the four phases of mitosis.
1)
3)
Prophase
Anaphase
2)
4)
Metaphase
Telophase