Mitosis in and Onion Root
Introduction: Mitosis can be observed in cells that are in a state of growth. In this lab, you will observe cells and identify which stage of cell division the cells are in. To help you do this, let's review what characteristics to look for at the different stages. Also remember, interphase is not technically a part of Mitosis, but it is part of the cell cycle and many of the cells you will be looking at are in interphase - so it is included in this activity.
Stage ...................................Distinguishing Characteristics
Interphase
Prophase
Metaphase
Anaphase
Telophase
Procedure: You will be given a slide of Allium, which is an onion root tip.
Growth occurs when cells divide, so the root tips should have several cells
in the process of cell division. View the root tip under the microscope and
search for organized blocks of cells where nuclei are plainly visible. (Most
activity will be occurring at the tip of the root). Move the slide around until
you find a good spot that shows the cells in various stages of mitosis. *Make-Up
work, see www.biologycorner.com/bio1/onionroot.html
Stage .................................................Sketch ................................................Estimated
Number of Cells in this Stage
Interphase
Prophase
Metaphase
Anaphase
Telophase
Analysis
1. Why is the onion root a good specimen for studying mitosis?
2. The majority of the cells in your specimen were in which stage of the cell
cycle?
3. In allium, interphase lasts about 15 hours, and mitosis takes up 80 minutes.
Assuming that each stage of mitosis takes the same amount of time, how many
hours old is a cell that is just starting anaphase. (Yes, you'll need to do
some algebra here - show your work)
4. Sketch one cell in any stage of mitosis. Label the stage and label any cell
structures that are visible. The spindle fibers and chromosomes should be visible.
5. Which stage of mitosis is the easiest (in your opinion) to see on the slide?
What about it makes it easy to identify?