Names:
Pd:
The Time of the Cell Cycle
Problem – How long do onion root tip cells spend in each phase of the cell cycle?
Objectives – In this activity, you will:
1.
2.
3.
4.
use the Internet to look at onion root cells.
identify the phases of the cell cycle for the onion root cells.
calculate the percentage of time an onion root cell spends in each phase of the cell cycle.
calculate the degrees of a pie chart for each phase and show your results in a graph.
Instructions:
1. Log on to www.biology.arizona.edu
2. Click on “Onion Root Tips” (under the Activities menu on the left side of the screen)
3. Read the passages and answer the following questions (click “Next” after completing the
questions to advance to the next page)
a. Why study root cells when looking for cells going through the cell cycle?
b. Name the phases of the cell cycle.
4. Read the instructions for “The assignment”…don’t worry about drawing the table.
5. Make a hypothesis of which phase will have the highest count of cells. (Do
this BEFORE starting the activity!!)
HYPOTHESIS:
6. Complete the assignment by clicking on which phase the cell belongs in.
7. After completing the assignment, count the number of cells in each column. Record this
number in the Data Table (on back) for that phase.
8. Total the number of cells in the activity. Record the total in the Data Table.
9. Calculate the decimal form for each phase and record it in the Data Table. To calculate this take
the number of cells in that phase and divide by the total. Round each decimal to the
thousandths place (Ex. 5/10 = .500).
10. Calculate the percentage of each phase and record it in the Data Table. To calculate the
percentage, take the decimal form for the phase and multiply it by 100 (or simply moving the
decimal 2 place to the right). Remember to include the % sign when you record it in the Data
Table. Total percentage row and record the number.
11. Calculate the number of degrees in a circle graph for each phase and record it in the Data Table.
To calculate degrees, take the decimal form for the phase and multiply it by 360 (because there
is 3600 in a circle. Remember to include the degrees symbols when recording your answers.
Total the degrees row and record the number.
12. Make a circle graph by: (choose one, not both)
a. using a protractor
- Obtain a circle graph and protractor from the teacher.
- Label each portion of the graph with the phase it represents and the percentage for
the phase
b. using Excel
- Type the name of the phases of the cell cycle in order under column A
- Type the number of cells for each phase under column B
- Highlight all the cells with your data
- Click on “Insert” and choose “Pie” under the Charts section, then choose the pie chart
of your choice.
- Then right click on chart and choose “Move Chart”, choose “New Sheet”
- Under the Chart Style section, choose the Black, White, Gray verison.
- Under the Chart Layout section, choose the one that will show the percentages and
the key (it is the middle icon)
- Print chart and staple it to your paper
13. Answer the questions in the Analysis and Conclusion section below the Data Table.
Interphase
Prophase
Metaphase
Anaphase
Telophase
Total
# of cells
Decimal
Form (.000)
% Form
Degrees
Analysis and Conclusion – Answer these questions in complete sentences.
1. In which phase of the cell cycle do the cells spend most of their time? Which phase do they
spend the least time?
2. What your hypothesis correct? Explain why or why not.