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Printed: January 15, 2015
AUTHORS
Jessica Harwood
Douglas Wilkin, Ph.D.
EDITOR
Douglas Wilkin, Ph.D.
CONTRIBUTORS
Doris Kraus, Ph.D.
Niamh Gray-Wilson
Jean Brainard, Ph.D.
Sarah Johnson
Jane Willan
Corliss Karasov

Chapter 1. Mitosis vs. Meiosis www.
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• Distinguish between mitosis and meiosis.
• Summarize the necessity for mitosis and meiosis.
Mitosis or Meiosis?
This represents a tiny embryo just beginning to form. Once an egg is fertilized, the resulting single cell must divide many, many times to develop a fetus. Both mitosis and meiosis involve cell division; is this type of cell division an example of mitosis or meiosis? The answer is mitosis. With each division you are making a genetically exact copy of the parent cell, which only happens through mitosis.
Mitosis vs. Meiosis
Mitosis, meiosis, and sexual reproduction are discussed at http://www.youtube.com/watch?v=kaSIjIzAtYA (18:23).
MEDIA
Click image to the left or use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/275
Both mitosis and meiosis result in eukaryotic cells dividing. So what is the difference between mitosis and meiosis?
The primary difference is the differing goals of each process. The goal of mitosis is to produce two daughter cells that are genetically identical to the parent cell, meaning the new cells have exactly the same DNA as the parent cell.
Mitosis happens when you want to grow, for example. You want all your new cells to have the same DNA as the previous cells. The goal of meiosis, however, is to produce sperm or eggs, also known as gametes . The resulting gametes are not genetically identical to the parent cell. Gametes are haploid cells, with only half the DNA present
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in the diploid parent cell. This is necessary so that when a sperm and an egg combine at fertilization , the resulting zygote has the correct amount of DNA—not twice as much as the parents. The zygote then begins to divide through mitosis.
Pictured below is a comparison between binary fission ( Figure
1.1
), which is cell division of prokaryotic organisms,
mitosis, and meiosis. Mitosis and meiosis are also compared in the table that follows ( Table
1.1
).
FIGURE 1.1
A comparison between binary fission, mitosis, and meiosis.
T ABLE 1.1: Mitosis vs. Meiosis: A Comparison
Purpose
Number of Cells Produced
Rounds of Cell Division
Haploid or Diploid
Daughter cells identical to parent cells?
Daughter cells identical to each other?
Yes
Mitosis
To produce new cells
2
1
Diploid
Yes
Meiosis
To produce gametes
4
2
Haploid
No
No
Summary
• The goal of mitosis is to produce a new cell that is identical to the parent cell.
• The goal of meiosis is to produce gametes that have half the DNA of the parent cell.
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Explore More
Use the resources below to answer the questions that follow.
Chapter 1. Mitosis vs. Meiosis
Explore More I
• Mitosis and Meiosis Simulation at http://www.youtube.com/watch?v=zGVBAHAsjJM (11:53)
MEDIA
Click image to the left or use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/57344
1. What are homologous chromosomes?
2. How do the location of specific genes compare between homologous chromosomes?
3. What is the outcome from mitosis?
4. What is a tetrad? Why are they an important feature of meiosis?
5. How does meiosis differ between females and males?
Explore More II
• How Cells Divide at http://www.pbs.org/wgbh/nova/body/how-cells-divide.html
1. How many daughter cells arise from mitosis? How many daughter cells are produced in meiosis?
2. How does the attachment of spindle fibers differ between mitosis and meiosis I?
3. Is anaphase I or anaphase II in meiosis more analogous to anaphase in mitosis? Explain your reasoning.
4. How many steps are there in mitosis? How many steps are there in meiosis?
5. How does interphase I of meiosis differ from interphase II of meiosis?
Review
1. What is the goal of mitosis? Of meiosis?
2. How many cells are created from cytokinesis following mitosis? Following meiosis?
3. Which process, mitosis to meiosis, creates genetically identical cells?
4. "Gametes are haploid cells." What does this sentence mean?
1. Zachary Wilson.
A comparison between binary fission, mitosis, and meiosis . CC BY-NC 3.0
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