BIOLOGY · CELL CYCLE INVESTIGATION

Mitosis & Cancer Cell Cycle Investigator

Examine tissue samples, classify cells, calculate mitotic index, and run cell-cycle regulation experiments. Your goal is not to diagnose cancer: it is to determine which tissue shows the strongest evidence that normal cell-cycle control has broken down.

Microscope evidenceMitotic index Cell-cycle regulationCER conclusion

STEP 1 · MICROSCOPY PRACTICE

Learn what the stages look like in a microscope

Real cells do not look as tidy as textbook diagrams. Use the reference guide, then classify six practice cells.

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VISUAL REFERENCE

Cell-cycle stage guide

Interphase

Intact nucleus; DNA is not condensed into visible chromosomes.

Prophase

Chromosomes condense and become easier to see.

Metaphase

Condensed chromosomes line up near the middle of the cell.

Anaphase

Sister chromatids separate and move toward opposite ends.

Telophase

Two new nuclei begin forming as chromosomes arrive at opposite ends.

PRACTICE CELL

Identify this stage

0 correct

Use chromosome position and nucleus appearance as evidence.

STEP 2 · TISSUE SAMPLES

Classify cells as interphase or mitosis

Analyze all 12 cells in each field. Select a numbered cell, then decide whether it is in interphase or mitosis.

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MICROSCOPE FIELD

Tissue Sample A

0 / 12 classified

Tip: Interphase cells usually have one intact nucleus. Mitotic cells show condensed or separated chromosomes.

STEP 3 · DATA ANALYSIS

Calculate mitotic index

Mitotic index is the percentage of observed cells that are undergoing mitosis. A high value can indicate rapid growth—but rapid growth does not automatically mean cancer.

MITOTIC INDEXcells in mitosis ÷ total observed cells × 100

Example: 3 ÷ 12 × 100 = 25%

YOUR COUNTS

Microscope evidence table

Sample	Interphase	Mitosis	Total	Your mitotic index	Check

Calculate all three mitotic indices to continue.

STEP 4 · CELL-CYCLE REGULATION

Test how each tissue responds to stop signals

Run all three experiments. Each test changes one condition while the same three tissue samples are observed for a simulated 24 hours.

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TISSUE CULTURES

Waiting for experiment

Ready

Sample A—

Sample B—

Sample C—

Choose a regulation test to begin.

EXPERIMENT LOG

Regulation-test evidence

Test	Sample A	Sample B	Sample C
Run a test to collect regulation evidence.

STEP 5 · EVIDENCE-BASED CONCLUSION

Which sample shows disrupted cell-cycle regulation?

Use both kinds of evidence: the microscope data and the regulation experiments.

YOUR CLAIM

Select the sample with the strongest evidence

Choose a sample, then support your claim with evidence.

Claim Evidence Reasoning

Model boundary

This investigation models a few major patterns of cell-cycle regulation. Real cancer diagnosis requires far more evidence than mitotic index or a simplified cell-culture response. The model is designed to help students reason about regulated versus dysregulated cell division.

Download Investigation Worksheet