Cancer & Mutation

Question 1

What are the features of cancer at the cellular level?

Answer 1

Uncontrolled cell division.
Change in morphology.
Dedifferentiation of cells.
Migration into adjacent & distant tissues.

Question 2

Define cancer.

Answer 2

A disease caused by the uncontrolled division of abnormal cells in a part of the body.

Question 3

What are the characteristics of cancer cells?

Answer 3

Uncontrolled growth
Loss of contact inhibited cell division
Immortal

Question 4

Describe the stages of tumour development.

Answer 4

1. Normal cells
2. Genes involved in growth and replication mutate
3. Rapid growth
4. Tumour forms
5. Malignant tumour eventually forms
6. Metastasis occurs and cancerous cells spread to other regions in the body

Question 5

Is cancer a genetic disease?

Answer 5

Yes, at the cellular level, cancer is caused by mutations of genes.

Question 6

Is cancer an inherited disease?

Answer 6

No, but some cancers show hereditary patterns.

This is only accounts for around 5% of all cancers.

Question 7

What types of environmental agents cause cancer?

Give examples.

Answer 7

Biological: Hepatitis B virus, Human papilloma virus
Chemical: Cigarette smoke, Heterocyclic amines in cooked meat
Physical: UV in sunlight, X-rays

Question 8

How does UV in sunlight cause cancer?

Answer 8

Energy from UV cause covalent bonds to from between thymine molecules

Question 9

What is a DNA adduct?

Answer 9

A segment of DNA bound to a carcinogen.

This could be the start of a cancerous cell.

Question 10

Aflatoxin is a toxic metabolite produced by a fungus which grows on crops like corn and peanuts.
How can it cause liver cancer?

Answer 10

When aflatoxin is metabolised in the liver, it forms a reactive intermediate.
This forms a DNA adduct that leads to liver cancer.

Question 11

What is the difference between ‘Case-control studies’ and ‘Prospective (cohort) studies’?

Answer 11

Case-control = Compares a disease group with a control group. Looking for factors that are more common in people with the disease.
Prospective = Follows a population over time, to see if the disease is linked to a suspected cause.

Question 12

Cancer is mainly caused by environmental factors, but genetic variation may contribute to the risk.
What is this?

Answer 12

Polymorphisms of the DNA repair gene.

Defects in DNA or DNA repair.

Question 13

How can you reduce the risk of cancer?

Answer 13

Don't smoke
Drink in moderation
Avoid too much time in the sun
Eat a balanced diet with lots of fruit & veg
Maintain a healthy weight