What Is Mitosis Actually For, and What Happens When It Goes Wrong?
Use a cell model to connect DNA, chromosomes, the cell cycle, mitosis, growth, repair, cancer, and stem cells.
Lesson Focus
Anchor question: how can one fertilized egg become a body with trillions of cells, and why is uncontrolled cell division dangerous? Today you will model mitosis as a process for making genetically identical body cells.
Section 1Hook: Where Is the DNA?~10 min
Reference
DNA carries genetic instructions. In eukaryotic cells, DNA is found in the nucleus.
Before a body cell divides, its DNA must be copied.
Mitosis separates copied chromosomes so each new cell receives the same instructions.
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Open the Cell Sim
Use the sim briefly to locate the nucleus and refresh your memory of why cells need organized parts before you model cell division.
Write down why DNA must be protected and copied before division.
3
Return to this page and use the model table to track chromosomes through mitosis.
Hook Note 1
Where is DNA found in the cell model?
Hook Note 2
Why would a new body cell need the same DNA instructions as the original cell?
Section 2Track the Cell Cycle~25 min
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Model check
Mitosis is only one part of the cell cycle. The cell grows, copies DNA, separates chromosomes, and then splits into two cells.
Stage
What Is Happening?
Why Does This Matter?
One Visual Clue
Interphase
Prophase
Metaphase
Anaphase
Telophase and cytokinesis
Checkpoint
Why must DNA be copied before mitosis begins?
Outcome
How many cells are produced, and how do they compare genetically?
Section 3Connect Mitosis to the Body~25 min
Situation
Is Mitosis Helpful, Harmful, or Both?
Explain Your Thinking
A scraped knee heals over several days.
A child grows taller over several years.
Cells divide even when the body does not need new cells.
Stem cells replace specialized cells in damaged tissue.
Cancer Connection
Cancer is often described as uncontrolled cell division. What control or checkpoint seems to have failed?
Use the words cell cycle, mitosis, DNA, and uncontrolled in your answer.
!
Final Task
Karen says, "Mitosis is just cells splitting in half, so the details do not matter." Correct her using DNA, chromosomes, and the purpose of mitosis.
Karen Prompt
Write a short correction. Include at least two stage names or cell-cycle terms.
Exit Ticket
Answer the anchor question: how can one fertilized egg become trillions of body cells, and why can uncontrolled division be dangerous?
Finished?
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