Cell cycle and mitosis
BiologyCell BiologyAges 15–16
Use it with your class: students open it from a link or a QR code, with no account needed.
Next in Cell Biology
The cell cycle ring runs G1 → S → G2 → M with a phase hand, three checkpoints, and a DNA-content graph; alongside it, an animated cell shows chromosomes duplicating in S phase, condensing in prophase, lining up in metaphase, separating to opposite poles in anaphase, and forming two daughter cells in telophase. Students choose the diploid chromosome number 2n and the speed, and can tap the ring to jump to a phase or pause it at a checkpoint. A Control and cancer view adds cyclin–CDK activity curves, p53 arrest and apoptosis, and a tissue in which oncogenes, lost tumour suppressors and mutagens produce benign or malignant tumours, with a cell-count graph and the mitotic index.
Lesson: The cell cycle, checkpoints, and mitosis
What it shows
The cell cycle alternates a long interphase (G1, S, G2) with a short M phase. In S phase each chromosome is replicated into two sister chromatids, so DNA content doubles from 2C to 4C while the chromosome number stays 2n. Checkpoints at G1/S, G2/M and the spindle stop the cycle until conditions are met; they are driven by cyclin–CDK complexes and by p53, which halts cells with damaged DNA or triggers apoptosis. The Control and cancer view shows how oncogenes, lost tumour suppressors and mutagens let cells divide uncontrollably and form benign or malignant tumours.
How to use
In Cycle and mitosis, let the cycle run with the DNA-content graph, then step through with Pause and Next phase, or stop at checkpoints and use Pass checkpoint. Switch View to Control and cancer: lower Growth factor to see the cell wait in G0, press Damage DNA to watch p53 stop the cycle, then tick Proto-oncogene → oncogene or p53 lost and follow the tissue, the mitotic index and the cell count.
Parameters you can change
- Diploid chromosome number 2n 2–8
- Simulation speed 0.25–3 ×
- Pause at checkpoints
- Show DNA-content graph
- View Cycle and mitosis, Control and cancer
- Proto-oncogene mutated into an oncogene
- p53 tumour suppressor gene lost
- Tumour suppressor gene silenced by methylation
- Growth factor level 0–2 ×
- Mutagen exposure 0–5 ×
Questions to explore
- How many separate chromosomes does a cell with 2n = 4 contain during anaphase of mitosis?
- Why does DNA content double in S phase while the chromosome number stays the same?
- What could happen to a cell if the G1/S checkpoint failed to detect damaged DNA?
