Uncontrolled Cell Division and Cancer
Joe Wolfensohn
Teacher
Contents
Recall Questions
This topic requires prior knowledge of mitosis and how regulatory mechanisms control cell division. You can test your knowledge on these below.
What is the role of mitosis in multicellular organisms?
Mitosis is essential for growth, tissue repair, and asexual reproduction.
Define a mutation.
A mutation is a change in the DNA base sequence of a gene.
What is the function of checkpoints in interphase?
To check for errors in DNA after replication before going into mitosis.
Topic Explainer Video
Check out this @JoeDoesBiology video that explains uncontrolled cell division and cancer or read the full notes below. Once you've gone through the whole note, try out the practice questions!
Introduction to Cancer
Definition: Cancer arises from uncontrolled mitosis, leading to the formation of tumours.
Causes of Uncontrolled Cell Division
Genetic Mutations: Changes in genes that regulate the cell cycle can lead to uncontrolled division.
- Oncogenes: Mutated genes that promote excessive cell division.
- Tumour Suppressor Genes: Genes that normally inhibit cell division; mutations can deactivate them, removing inhibition of cell division.
Mutagenic agents: Agents that increase the frequency of mutations potentially leading to cancer. Examples include:
- Ultraviolet (UV) light.
- Benzene in tobacco smoke.
- X-rays.
- Gamma rays.
- Human Papilloma Virus (HPV).
Formation of Tumours
Process:
- Mutations occur in genes controlling cell division.
- Cells begin to divide uncontrollably.
- A mass of abnormal cells, called a tumour, forms.
- More detail about the control of oncogenes and tumour suppressor genes will be covered in year 13, module 8.
Types of Tumours:
- Benign Tumours: Non-cancerous growths that do not spread to other parts of the body.
- Malignant Tumours: Cancerous growths that invade neighboring tissues and can spread (metastasize) to other parts of the body via the bloodstream, where secondary tumours can develop.
Metastasis
- Definition: The spread of cancer cells from the original site to other parts of the body via the blood and lymphatic systems.
- Impact: Makes cancer more difficult to treat and can lead to formation of secondary tumours.
Cancer Treatments
- Chemotherapy: Uses drugs to target and kill rapidly dividing cells.
- Radiation Therapy: Uses high-energy radiation to destroy cancer cells.
- Surgery: Physically removes tumours from the body.
Key Terms
- Oncogene: A mutated gene that promotes uncontrolled cell division.
- Tumour Suppressor Gene: A gene that inhibits cell division; when mutated, it can lead to cancer.
- Metastasis: The spread of cancer cells via the blood stream or the lymphatic system to other parts of the body.
- Carcinogen: A substance capable of causing cancer.
- Mutagenic agent: Agents that increase the frequency of mutations potentially leading to cancer.
No answer provided.
Exam Tips
Link Causes and Effects: Connect exposure to mutagenic agents with the potential for DNA mutations and cancer development.
No answer provided.
Describe the differences between benign and malignant tumours. (2 marks)
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Benign tumours grow slowly and are enclosed in a capsule, so they do not invade other tissues or spread to other parts of the body.
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Malignant tumours grow rapidly and are invasive, potentially spreading via the blood or lymph to form secondary tumours (metastasis)
Practice Question
Try to answer the practice question from the TikTok on your own, then watch the video to see how well you did!