I. Counting the Number of Cells in Each Phase of Mitosis

Time For

Mitosis

I. Counting the Number of Cells in Each Phase of Mitosis

·  Use the following website to complete the lab activity:

http://www.biology.arizona.edu/Cell_BIO/activities/cell_cycle/cell_cycle.html

·  You will be asked to look at cells in different phases of mitosis and categorize them.

·  Once you have counted all the cells, record your data in the table at the bottom of the page.

II. Determine the Time Required for Each Phase

·  Onion cells need 12 hours (720 minutes) to complete the cell cycle. You are going to calculate the time spent in each phase of the cell cycle. Assume the number of cells in each phase is an indication of the time spent in each phase. The amount of time needed for the phases can be calculated by the following formula:

·  Calculate the time required for each phase of the cell cycle using your data and record your results in the table at the bottom of the page.

Table 1

III. Constructing a Pie Graph

·  Using your data from Table 1, create a pie graph which shows the number of minutes that onion cells spend in each phase of the cell cycle.

·  The circle is divided into smaller sections. Each section is equal to 18 minutes. If a phase is not exactly 18 minutes long, approximate the position of the line on your graph.

·  Shade each phase on your graph with colored pencils.

·  Identify each phase by shading in the key to correspond with the shade on your graph.

IV. Analysis Questions

1. Which phase requires the longest time for completion?

2. Which phase requires the next longest time for completion?

3. Which phase requires the shortest time for completion?

The following table shows the average times required for normal and diseased chicken stomach cells to complete the cell cycle.

4. In normal chicken cell, which phase requires the longest time for completion?

5. In normal chicken cells, which phase requires the next longest time for completion?

6. How do your answer to questions 4 and 5 compare with questions compare with questions 1 and 2?

7. What is the total time needed for a normal chicken stomach cell to complete the cell cycle? (Add up the times for all phases of the cell cycle.)

8. What is the total time needed for a cancerous chicken stomach cell to complete the cell cycle?

9. How do cancer cells differ from normal cell in their total time required for the cell cycle?

10. How do cancer cells differ normal cells in time spent in each individual stage?