Mitosis Lab
This lab involves the study of a slide of dividing cells in the root-tip meristem and the embryonic
cells of the whitefish blastula. These are areas where cells are dividing at a rapid rate. Obtain a
slide of representative plant and animal mitotic tissue (onion root tip and whitefish blastula).
Some students will start with the plant cells and some will start with animal cells.
1. Observe your root tip preparation under low power and sketch the general features in the
space provided below.
2. Once the cells are in focus, switch to high power and identify the different phases of mitosis
and make drawings of each phase.
Prophase
Metaphase
Anaphase
Telophase
3. Find a cell in which the chromosomes are spread out, and try to count the chromosomes in
the cell. You may want to count the chromosomes in several cells to get a more accurate
reading. Record your findings.
4. Cells spend most of their time in Interphase of the cell cycle. Write a hypothesis about what
stage of mitosis will be found at the highest frequency in these cells
(If……..then…….because…….).
5. Find 200 mitotic figures and score the number of prophases, metaphases, anaphases and
telophases in those 200 mitotic cells. Use the following chart to determine the percentage of
time a typical cell spends in each of the mitotic phases.
Number of
Mitotic Cells
Percentage of Time
Class Average
Total # of cells
200
100
100
Number in prophase
Number in metaphase
Number in anaphase
Number in telophase
To estimate the percentage of time occupied by each mitotic phase, use the following equation:
Phase Percentage = (# of cells in a phase / total # of cells) x 100
5. Before removing the slide, note how cytokinesis occurs in plants. Draw that process here.
6. Now sketch the mitotic stages of the whitefish blastula.
Prophase
Metaphase
Anaphase
Telophase
7. Calculate the percentage of cells in the various stages of mitosis in the whitefish blastula using
the same methods you used for the root tip preparation.
Number of Cells
Percentage of Time
Class Average
Total # of cells
Number in prophase
Number in metaphase
Number in anaphase
Number in telophase
200
100
100
8. Compare the percentages of time occupied by the various mitotic phases in the whitefish
blastula (embryos) with those in the plant meristematic tissue.
9. Observe cytokinesis in the whitefish blastula. Based on your observations, is there a difference
between animal and plant cytokinesis?
10. Now create a graph using your own data showing the percentages of time spent in each of the
four mitotic phases. Please use graph paper provided. Label title and axis properly.