Unchecked Cell Growth
We have learned about the cell cycle in previous lessons. A typical cell goes through the cell cycle in one to two days. The cell cycle is told to start or stop by chemical signals. For instance, if you get a paper cut, the cells in your finger get the message to start dividing to repair the damage.
If a cell ignores the message to stop dividing, unchecked cell growth can occur. Over time, a mass of cells, or tumour, can form.
So, why do some cells get confused and refuse to stop dividing?
The typical answer is that a mutation occurs. A mutation is a permanent change in a cell's DNA. Sometimes a mutation results in a cell going deaf to the signal to stop dividing. Some mutations are inherited, while others are the result of exposure to environmental conditions. More about that later.
Tumours
Not all tumours are cancerous. Different mutations will produce different types of tumours.
Benign Tumour
- cell division is unchecked
- cell division occurs at a moderate rate
- tumour does not invade adjacent cells, but may crowd out its neighbours
- does not spread throughout the body
- fairly harmless (unless in the brain, where it may cause traumatic pressure)
Cancerous Tumour
- cell division is unchecked
- cell division occurs rapidly (a very small amount of time is spent in interphase)
- tumour invades adjacent cells and damages them
- may spread to throughout the body
- may interfere with the proper function of other cells
- may result in death if the tumour is not destroyed or removed
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| Cancer cell being attacked by lymphocytes (a type of white blood cell). |
Staying Healthy
So, how can you lessen the likelihood that you will get cancer?
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