This document provides an overview of mitosis in plant and animal cells. It describes the stages of the cell cycle and mitosis, including interphase, prophase, metaphase, anaphase, telophase, and cytokinesis. Students are instructed to observe prepared slides of onion root tips and whitefish blastula under a microscope to identify cells in each stage of mitosis. Key differences between mitosis in plant and animal cells are highlighted, such as the formation of cell walls in plant cell cytokinesis. The role of mitosis in cellular reproduction is also discussed.

1. Bio 103 - Introduction to Biology
Chapter 8: Cellular Reproduction: Cells from Cells
Mitosis in Plant and Animal Cells
Background: All cells undergo a process of growth and division called the cell cycle. The cell cycle consists of
three major stages-interphase, mitosis, and cytokinesis. During interphase, the cell grows and, at the end, the
cell's DNA replicates. Most of a cell's life is spent in interphase. The next phase is mitosis, during which the
replicated genetic material separates into two separate nuclei. Mitosis is further divided into four stages:
prophase, metaphase, anaphase, and telophase. Two identical nuclei result from mitosis. Cytokinesis, the last
stage of cell division, is the division of the cell cytoplasm between the two newly forming cells. The completion
of the cell cycle results in the formation of two genetically identical daughter cells from the division of a
parent cell.
Objectives:
• Identify cells undergoing the process of mitosis.
• Compare the stages of mitosis in plant cells with these stages in animal cells.
Materials:
• prepared slides of onion or garlic root tips (longitudinal sections)
• compound light microscope
As this is an online class and you don’t have access to microscopes or slides, the images as one would see
through a compound light microscope are included for your observations.
Procedure: PART 1: Mitosis in Plant Cells
1. Observe a prepared slide of a longitudinal section of onion or garlic root tip.
Use low power to locate the region of actively dividing cells near the end of the root. Then using high power,
examine individual cells in the region. Find a cell from each stage of mitosis using the descriptions in the list
below. In the space next to each description, draw a cell in that stage as it appears on your slide.
Again, as this is an online class and you don’t have access to microscopes or slides, use the images provided as a
substitute for your observations.
Interphase
This is the phase of normal cell activity. During interphase, individual
chromosomes cannot be distinguished. Instead, they appear as a dark mass
of material called chromatin (label C). The DNA of each chromosome replicates
at the end of this stage. Note the nucleus with one or more dark-stained
nucleoli (label I) filled with chromatin.
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success = preparation + execution

2. Prophase
In this stage, the chromatin appears as a mass of thick threads. These
threads are the replicated chromosomes, which have coiled up and
shortened. Each chromosome now consists of a pair of chromatids, which
are duplicates of the original chromosome. The chromatids are held together
by a centromere. In late prophase, the nuclear membrane and nucleoli
cannot be seen, but the chromosomes are distinctly visible as pairs of
chromatids in the central region of the cell.
Metaphase
In this stage, the chromosomes line up across the equator of the cell (label
Ch). A mass of fibers called a spindle (label S) has formed between the
poles of the cell and the mass of chromosomes. A spindle fiber from each
pole attaches to each chromosome (pair of chromatids).
Anaphase
In this stage, the centromere of each chromatid pair divides. The chromatids
move along the spindle fibers toward the poles of the cell. Each chromatid in
the pair of chromatids moves toward opposite poles of the cell.
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3. Telophase
In this stage, the chromatids (now called chromosomes) have formed
distinctive clumps at each pole. A new nuclear membrane forms around
each clump of chromosomes, which uncoil and return to the chromatin
network seen in interphase. The nucleoli reappear. In plants, the new cell
walls (the arrows in both pictures) grow to form the two new, identical
daughter cells.
Analysis: Complete the following questions using information from this
laboratory activity.
1. What is the shape of the cells?
2. What color are the chromosomes stained?
3. What happens during cytokinesis?
4. How many new cells have formed from the parent cell?
Procedure: PART 2: Mitosis in Animal Cells
2. Observe the prepared slide of the whitefish blastula. Locate the blastula using low power, then examine it
under high power. Find a cell from each stage, using the list below. In the space beside each description, draw a
cell in that stage as it appears on your slide. Label the parts of the cell that are visible.
Interphase
A distinct nucleus and a nucleolus (label C) are visible. The
genetic material appears as chromatin.
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4. Early Prophase
Astral rays have formed around the centrioles,
and the spindle (label A) has formed between
them. The chromosomes (paired chromatids) are
becoming visible, and the nuclear membrane has
disappeared.
Late Prophase
The chromosomes are shortened and thickened
and are distinct in the central region of the cell.
Metaphase
The chromosomes line up at the center of the
cell, along the equator (label C). The astral rays
are also visible (label A).
Anaphase
The chromatids (label B) separate at their
centromere and are pulled to opposite poles along
the spindle fibers (label A).
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success = preparation + execution

5. Telophase
The chromosomes appear in clusters at the poles.
The parent cell begins elongating, and the nuclear
membranes re-form around the chromosome
clusters. The spindle and chromosomes become
less distinct. The cytoplasm pinches (label A) in
until the two daughter cells separate during late
telophase.
Analysis:
5. What is the shape of the cells?
6. Describe the shape of the chromosomes as they are pulled to the poles in anaphase.
7. At the completion of cytokinesis, in what phase are the two daughter cells?
8. How does mitosis differ in plant and animal cells?
9. Which phase of mitosis shows the greatest difference between animal and plant cells? Explain your choice.
10. What role do you think mitosis plays in living things? Justify your answer.
11. Mitosis in onion root tip cells takes about 80 minutes. If you view a slide of a root tip and count the number
of cells in each stage of mitosis, you can then calculate the amount of time each stage takes. This is because the
percentage of the cells in a particular stage of mitosis is equal to the percentage of 80 minutes that the stage
takes. Using this information, devise a method for calculating the amount of time each stage of mitosis takes.
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success = preparation + execution