In this topic we are learning to: z Examine how mutation introduces variation into a population. z Explain the causes and treatments for certain cancers.
z Consider the role of mutation and inheritance in common genetic disorders.
Mutation is a change in a gene or chromosome.
Like other causes of variation, mutation can be inherited or influenced by an organism’s environment.
Treatments
Current treatments for cancer include surgery, radiotherapy, chemotherapy, biological therapies or a combination of these treatments. Research these treatments and prepare a short report on each for your classmates.
Mutation can also happen randomly. Mutations may be useful to an organism, but they can also be harmful.
Cancer
Cells are constantly dividing. Mutated cells divide much more quickly than normal cells. This can cause a mass of cells called a tumour to form. z Benign tumours do not move to other parts of the body. z Malignant tumours can spread and are more of a concern.
The group of diseases resulting from this type of mutation is called cancer. There are approximately 200 different cancers.
Most cancers are not inherited. Certain cancers become more common as people age, such as prostate cancer in males and ovarian cancer in females.
It is important that people are aware of the signs and symptoms of cancer. The earlier the disease is diagnosed, the less likely it is to spread and the sooner treatment can start. This greatly improves the chances of recovery.
Causes of Mutation
While most mutations are completely random, they can also happen because of certain environmental factors.
For example:
z Smokers are at far greater risk of developing lung cancer than non-smokers.
z Ultraviolet (UV) rays in sunlight destroy the DNA of skin cells. People who spend too long in the sun without applying sunscreen and those who use sunbeds increase their risk of skin cancer.
Fig. 4.3.1 A man wearing a protective anti-radiation suit 72 72
z Exposure to gamma rays or X-rays can cause mutation.
Any environmental factor that increases the likelihood of mutation is called a mutagen.
