Lab: Cell Division
Goals: Today’s activity will help you understand the phases of the cell cycle in somatic
cells. You will:
1. examine slides of an onion root tip.
2. engage in a on-line onion root tip lab.
Part A. Examining root tip cells. When you examine a cross section of a root tip, you
will see lots of cells. These cells will be in different growth stages (different parts of the
cell cycle).
Materials:
Microscope
Prepared slides of an onion root tip
Procedures
1. Examine the slide using the compound light microscope according to the procedure
learned in the previous lab activity with microscopes. Note - you may need to review the
procedures for using the microscope before beginning this activity.
a. What do you notice about the various growth stages?
b. How many stages do you see?
2. What does this tell you about cell division? Would you expect to see the same stages
of growth in other tissues of the onion plant? Explain your answer.
Part B. Learn about the cell cycle. You can continue to learn many interesting things
about the cell cycle by going to
http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html.
Read the information on this website and watch the cell’s nuclear material replicate and
divide. Remember that the two cells will pull apart and each “daughter cell” will
continue the process. This will result in tissue growth and repair. As you work through
the activity, you will fill in the chart below.
Interphase
Prophase
Metaphase
Anaphase
Telophase
Number
of cells
Percent of
cells
1. Graph the stages.
Contemporary Issues in Biology: A Module for Teacher Training
Funded by Texas Higher Education Coordinating Board and Texas Education Agency
Developed at Texas Christian University
Total
36
100%
2. Identify which growth stage is most common and explain why.
3. Most textbooks say that the typical cell is in interphase for about 90% of the time.
Compare this with your data. Explain why your data matches or does not match
the textbook.
4. Why is mitosis important?
5. Using the information you learned about cancer in class, how does cancer affect
the rate of mitosis and the normal cell life cycle.
6. How would a slide of cancerous cells look different from this one?
Contemporary Issues in Biology: A Module for Teacher Training
Funded by Texas Higher Education Coordinating Board and Texas Education Agency
Developed at Texas Christian University