(Dr. Heinemann) (Unit C) Topic 17

Question 1

Benign vs. Malignant cancers

Answer 1

• Benign: Do not spread
• Malignant: Cells have the ability to invade surrounding tissues

Question 2

Why is cancer a genetic disease?

Answer 2

Cancer is caused by many damages to DNA

Question 3

What are cancer-causing agents?

Answer 3

• Radiation
• Chemical mutagens

Question 4

What forms of cancer ccan be inherited?

Answer 4

• Skin cancer
• Colon cancer
• Breast cancer
• Others

Question 5

True or False:

A single mutation is sufficient for cancer

Answer 5

False, cancer requires many accumulated mutations

Question 6

How many mutations is it estimated to be required for cancer to develop?

Answer 6

10 or more mutations

Question 7

What are 4 properties of cancerous cells?

Answer 7

1. Do not respond to signals that normally control cell division
2. Not sensitive to normal pathways of cellualr differentiation or programmed cell death (apoptosis)
3. Genetically unstable
4. Can escape their normal environment and proliferate at foreign sites (metastasize)

Question 8

It has been estimated that – percent of cancers are due to smoking

Answer 8

30%

Question 9

Aflatotoxin

Answer 9

A mold toxin
* Potent carcinogen
* Can be found in contaminated peanuts

Question 10

How do fruits and vegetables act as cancer inhibitors?

Answer 10

Act as free radical scavengers and thus reducing DNA damage

Question 11

What can HPV cause?

Answer 11

Cervical cancer

Question 12

Hepatitis B infections make patients more prone to:

Answer 12

Liver cancer

Question 13

What are the two types of cancer-causing genes?

Answer 13

1. Oncogenes
2. Tumor Suppresors

Question 14

Oncogenes

Answer 14

Genes whose presence in an aberrant form causes cancer

Question 15

How can oncogenes be aberrant?

Answer 15

1. Localization of the protein product
2. Activity of the product
3. Having too much of the product expressed

Question 16

Tumor Suppresor Genes

Answer 16

Genes whose absence causes cancer

Question 17

What are Tumor Suppresor Genes often involved in?

Answer 17

1. DNA repair
2. Control of cell growth/differentiation
3. Cell death

Question 18

What classes can cancer-causing genes be ROUGHLY divided into?

Answer 18

1. Growth factor receptors insensitive to normal signals/contitutively active
2. Enzymes in cell signalling cascades inappropriately active
3. Molecules that are normally involved in programmed cell death/determine cellular longevity
4. Molecules that directly control cell division (check point controls)
5. Molecules involved in repairing DNA damage/reducing damage from oxidative stress
6. Factors that are involved in expression of other genes (transcription factors etc.)

Question 19

Why are cancers difficult to treat?

Answer 19

Cancer arises from a different combination of mutations
* Cancers of the same tissue may not be of the same genetic origin