Cell Mitosis

Introduction

Mitosis is the process of cellular division that results in two identical daughter cells (with the same number of chromosomes as the parent cell). Mitosis is used for growth and repair, regeneration and asexual reproduction. In this experiment, you will determine the duration of each phase of mitosis in onion root tissue, in an area called the apical meristem. In many plants, mitosis occurs only in meristem regions, which located at the tips of roots and stems.

Materials:

• Prepared slide of onion root tip
• Compound microscope
• Microscope slide and coverslip

Instructions

View the slide under high power. Observe each cell and determine what phase of mitosis it is undergoing. Do not worry about distinguishing prophase from prometaphase. Count a minimum of 200 cells, changing your field of view as many times as necessary. Use this data to calculate the percentage of cells in each phase of mitosis. At any given time, about 90% of cells will be in interphase because it is the longest stage of the cell cycle. Do your observations agree with this?