Mitosis and the Cell Cycle (2025)
The stages of mitosis and the role of interphase
Mitosis is a miraculous process. In the making of the three trillion cells of our bodies it manages to faithfully replicate and share the chromosomes equally between all the daughter cells. This lesson focuses on the key details of mitosis and activities using an interactive animation and some questions help students to make sense of these details in the context of the whole process of mitosis.
Lesson Description
Guiding Questions
What are chromosomes?
How do cells divide their nucleus in two?
What do you think is happening to the chromosomes in the two cells in the diagram?
What happens to double the amount of DNA inside the nucleus during interphase?
Activity 1 - Introduction to Mitosis
Study this short video which describes the process of mitosis. It has lots of detail, and is clearly explained.
3D animation from VCell project. A short summary of mitosis is followed by detail of each phase.
Keep a mental note of what happens to the chromosomes in each of the main stages.
Prophase, Prometaphase, Metaphase, Anaphase, and Telophase.
For further information
A detailed written description of Mitosis by Michael W. Davidson from Florida State University.
Activity 2 - Mitosis Summary Activities
Using the video animation in Activity 1 complete the Student activities on mitosis shown below.
Try these IB style questions on mitosis and the cell cycle
Activity 3 - Identify the stages of mitosis in human cells
The stages of mitosis in theoretical diagrams of chromosomes are often used to explain the process of mitosis. In real tissue samples the task is more challenging because the alignment of the spindle in metaphase and anaphase can be in any orientation. For example, two groups of dividing chromosomes in anaphase can be visible over the top of each other.
This illustration shows views of anaphase from different perspectives.
Study the shapes of the nuclei in the images below and try to identify which phase of mitosis for each of the cells circled in green. Most of the cells surrounding these highlighted ones are in interphase.
Complete the notes on the Identifying the stages of mitosis student sheet.
Activity 4 - Extension questions - Cancer and the digestive tract
Try this data analysis activity about mitosis. This link to mitosis is not immediately obvious, this is the sort of question which tests a students ability to work out what is happening in a specific biological study which they haven't seen before.
- Why do some 'villi' grow longer than others?
- What causes growth?
The evidence in the study supports the concept of deregulated mitosis in the small intestines, which may cause cancer.
Cancer and the digestive tract - linking cell division, cancer and histology
Teacher only boxTeachers notes
Activity 1 - A good way to run this lesson is either to demonstrate the animation on the white board, or give the students access to the page, and let them explore the animation in Activity 1 at their own pace.
Activity 2 - Using this information about mitosis students can complete these Student activities on Mitosis which focus on the movement of chromosomes at the different stages of mitosis
The card sort will help students to make structured notes and the activity helps students to understand the details of mitosis,
There is a short set of IB style questions to give students a chance to express their knowledge and understanding of mitosis in a more formal way.
There are some white board slides showing notes about mitosis and model answers here:
An interesting addition to this activity would be to give students an "Info card" to 'play' during a lesson at a suitable moment. This allows them to interrupt and explain a crucial detail from lesson 1,
Cards could include:
- Equal cytokinesis, organelles duplicated too, or
- DNA replication is a prerequisite of cell division, or
- Differences between cytokinesis in plant and animal cells. or
- Histones are proteins involved in condensation of DNA to form chromosomes ****
Alternative ideas
Some classes may wish to try the technique on prepared slides of onion or garlic root tip cells as an extension activity.
If a wet lab is also wanted there are some good resources Mitotic index experiments on this website.
These ideas look great for building models to illustrate the cell cycle and mitosis. Cell cycle on a plate, and using wool in mitosis diagrams. (Images borrowed from Mrs Stevens' Science classes blog )
Onion or Garlic root tip experiments
The cells in an onion root can quite easily be used to calculate the mitotic index and this is a good learning exercise. The cell outline in plant cells is much clearer than it is in human cells. The onions, or garlic can be grown in the lab, Allium species is mentioned in the speciation section of genetics because they illustrate cases of speciation by polyploidy. However diagnosis of cancer in onion roots is one step further away from learning about the actual clinical value of the mitotic index.
Legacy link to the old student worksheet Cancer and the cell cycle - student worksheet
and the Mitotic index worksheet - model answers for the two conclusion questions
An alternative activity which I didn't use in the lesson but which might be useful for extension or for HL classes are
- Mitosis puzzle - a visible thinking activity
Activity 3 - Recognising mitosis - Students are first guided through the identification of cells in different stages of mitosis. It is important that students have a basic reference document for the stages of mitosis, as this activity builds on the simple and clear explanations of chromosome movements during mitosis.
The slide shows 12 different views of human cells performing mitosis taken from biopsy sample of breast tissue. It is normal that there is some doubt in the identification of these cells, real pathologists must also find this difficult.
Model answers can be found on this page: Identifying stages of mitosis - model answers (access to this page can be controlled in the Student access area) and in the slides on the model answers page I have sketched a diagram of each cell, to try to show the process of identification of the stage of mitosis. Of course, just like real pathologists, your intermretation may be different from mine, but the slides were originally identified in this research paper, Evaluation of Mitotic Activity Index in Breast Cancer Using Whole Slide Digital Images, published 30 Dec 2013 PLOS ONE
The student's worksheet asks the students to suggest an identification of the phase of mitosis. The command term suggest is used when there is an element of doubt about the interpretation of data, so this may be a good opportunity to alert students to this possible which doesn occur occasionally in IB DP Biology exams. It is also an opportunity to make a link to TOK, because the reliability of scientific data does depend on human interpretation.