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Mitosis and the Cell Cycle - How a Single Cell Develops into the Trillions of Cells in a Human Body

Cell cycle producing daughter cellsIn this hands-on, minds-on activity, students use model chromosomes and answer analysis and discussion questions to learn how the cell cycle produces genetically identical daughter cells.

Students learn how DNA replication and mitosis ensure that each new cell gets a complete set of chromosomes with a complete set of genes.Students learn why each cell needs a complete set of genes and how genes influence phenotypic characteristics.

To understand how a single cell (the fertilized egg) develops into the trillions of cells in a human body, students analyze an exponential growth model of increase in number of cells. The final section provides a very brief introduction to cellular differentiation. 

This activity can be used as an introduction to mitosis or to reinforce understanding of mitosis. 

In our follow-up meiosis and fertilization activity (/sci_edu/waldron/#meiosis) students learn how the movement of gene-carrying chromosomes during meiosis and fertilization results in the inheritance of genes. (NGSS)

Download Student Handout: PDF format or Word format

Download Teacher Preparation Notes: PDF format or Word format

The Teacher Preparation Notes provide instructional suggestions and background information and explain how this activity is aligned with the Next Generation Science Standards. A remote-ready analysis and discussion version of the Student Handout is available at The attachments below provide the older version of the Student Handout in case you have already made model chromosomes and do not want to change the symbols for the alleles of the genes.

MitosisProtocol 2020.docx3.38 MB
MitosisProtocol 2020.pdf1.3 MB


iwaldron's picture

September 2021 revision

The September 2021 revision improved the wording of some questions and improved some of the figures in the Student Handout and clarified some points in the Teacher Preparation Notes.

Ashley Williams's picture

Key for teachers

Is there an updated email to receive a key for Mitosis and the Cell Cycle - How a Single Cell Develops into the Trillions of Cells in a Human Body? I tried to send to the email listed on page 6 and it bounced back.


iwaldron's picture

Email address

My email address continues to be I suspect there might have been a typo when you sent the message that bounced, so please try again.

iwaldron's picture

2021 revision

We have added a brief section on cell differentiation to help students understand that the cell cycle and mitosis are not the only processes needed to make a human body. In addition, we have changed the symbols for the alleles of the genes on the model chromosomes to avoid confusion between lower case and capital letters (e.g., s and S). If you have already made model chromosomes and do not want to change the symbols, we provide the older version of the Student Handout for your convenience.


iwaldron's picture

2018 revision

In the 2018 revision, we have included an expanded explanation and questions about the cell cycle to help students understand the context for mitosis. Also, we have reorganized the sequence and revised multiple questions to promote student understanding of the basic process of mitosis.

iwaldron's picture

2017 revision

The Student Handout has been substantially revised to engage students in more active learning and clarify the instructions, questions and explanations. We have added a focus on how a single cell, the zygote, develops into the trillions of cells in a human body, while maintaining our previous focus on the concepts of genes, chromosomes and how mitosis produces two daughter cells, each with a complete set of genes.

 Tran V's picture

Answer key

Can you please provide an answer sheet in order for us to correct our work, because we don't have time to read through all the notes. The teacher note attached are too much, it's 12 pages totally, and weare in a hurry. We just want the answer key to check our work.


iwaldron's picture


If you do not have time to read the Teacher Notes, I encourage you to look at the underlined terms and you will find the information you need.


Serendip Visitor's picture


I read the teacher preparation notes and I felt prepared to complete the activity myself. I think I did well but I would really like the answer to check to see if I completed the activity correctly.

iwaldron's picture

Answer key

Please see page 6 in the Teacher Preparation Notes.


Serendip Visitor's picture

Sickle cell trait?

You have mistakenly used sickle cell as an example of a recessive gene, whereas in fact it is co-dominant, meaning people with one copy of the sickle allele have some health problems associated with the allele; this condition Ss is called sickle cell trait. Importantly, you should also explain why sickle cell trait has been conserved in the population, as it has adaptive advantages in populations who have exposure to malaria, as the parasite will not affect sickle cell trait sufferers but will affect those with normal haemoglobin.

iwaldron's picture

Sickle cell trait

Your points are well-taken and are briefly described on page 10 of the Teacher Preparation Notes for this activity. In addition, these points are developed on page 6 of the Student Handout for "Genetics" (/sci_edu/waldron/#genetics).

My own inclination is that it is reasonable to postpone introducing these points until after the mitosis and meiosis and fertilization activities which are designed to precede the genetics activity. Please note that we do not describe the sickle cell allele as recessive, but only state that a heterozygous individual does not have sickle cell anemia, a statement which is correct since a heterozygous individual almost never experiences the symptoms of sickle cell anemia. However, I can understand if you and some other teachers feel that the points you have raised should be introduced from the beginning of the discussion of the sickle cell allele and welcome you to prepare a modified version of the Student Handout for your students.


iwaldron's picture

November 2015 revision

Based on teacher feedback, the questions, explanations and figures in the Student Handout have been revised and reorganized for greater clarity and better focus on the most important concepts. In addition, we have developed a shorter and somewhat simplified version of the Student Handout which is appropriate for middle school and some high school students. The Teacher Preparation Notes have been revised for greater clarity and completeness.

Serendip Visitor's picture


I used paper chromosomes instead and they worked as well. I also had the students draw the cells on their desk in chalk and put the chromosomes in the cells.

Audrey Daubenmerkl's picture


I'm having trouble visualizing the rollosomes and how to make them. Would it be possible to post a picture? I'm also confused about how the groups share the rollosomes. I have 7 groups of 4 students, so do need 4 sets of 8 rollosomes?

Adrienne M's picture

rollosome mods

Just a tip, I did see the foam rollers at the dollar store last week.

But, what I used were part of a "toobers and zots" kit. I had bought those kits to do protein folding, and there were all these extra foam pieces, some of which are like mini pool noodles.

Serendip Visitor's picture



I am confused regarding the answers. I would like them for corrections.

Mr. Strauss

iwaldron's picture

How to Find the Answers for This Activity

To find the answers for the questions in this activity, please first read the Teacher Preparation Notes available on this website and then follow the advice in those notes to get additional information.


iwaldron's picture

February 2015 revision of mitosis activity

The major improvement in this mitosis activity has been a more structured approach to student modeling of mitosis, including clarified directions and the addition of diagrams where students record the results of their modeling. The instructions for making model chromosomes have also been streamlined. We are grateful to local teachers who provided helpful suggestions for improvements.

iwaldron's picture

New and Improved Mitosis, Meiosis and Fertilization Activities

We have split our older mitosis, meiosis and fertilization activity into two enhanced closely-linked activities:

  • Mitosis – How Each New Cell Gets a Complete Set of Genes
  • Meiosis and Fertilization – Understanding How Genes Are Inherited

Major enhancements include:

  • more explicit discussion of the links between genotype and phenotype
  • more discussion of how meiosis and fertilization result in genotypic and phenotypic variation in offspring (with explicit discussion of independent assortment and crossing over)
  • clarification of many of the questions and instructions for using the model chromosomes
  • increased background information in the Teacher Preparation Notes.

Teachers who have previously made the model chromosomes for our earlier activity, "Mitosis, Meiosis and Fertilization", can find the Student Handout and Teacher Preparation Notes for that older activity at /exchange/waldron/mitosismeiosis . However, we encourage you to modify your model chromosomes for use in this new pair of activities, since we believe this version will enhance student understanding of important concepts.

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