Chapter 5: 5.11 Molecular Basis for Cancer

Question 1

Cancer arises when…

Answer 1

Cells grow or divide out of control

Question 2

What causes cancer?

Answer 2

Mutations in many different types of genes

Question 3

Cancer is caused by mutations in genes that control…

Answer 3

1. Cell growth
2. Cell division
3. Apoptosis
4. DNA repair
5. Growth at foreign sites

Question 4

Describe:

Cell growth genes in cancer

Answer 4

Signals that tell the cell to stop growing are mutated
* Thus, once cells grow to a certain size, they divide

Question 5

Describe:

Cell division genes in cancer

Answer 5

Signals that tell the cell to stop dividing are mutated

Question 6

Describe:

Apoptosis genes in cancer

Answer 6

Signals that control cell death are mutated
* Allols an abnormal cell to evade death (immortalized)

Question 7

Describe:

DNA repair genes in cancer

Answer 7

Mutations can arise more eaily in genetically unstable cells

Question 8

When does metastic cancer occur?

Answer 8

Cells from the primary tumor move to another part of the body and begin to grow there

Question 9

Define:

Benign cancer

Answer 9

Contained at the originating tissue

Question 10

Define:

Malignant cancer

Answer 10

Spreads to other tissues

Question 11

True or False:

Cancer can be inherited

Answer 11

True

Question 12

List:

DNA damaging agents

Answer 12

• UV
• Chemical agents
• Radiation etc.

Question 13

The more mutations that accumulate, the more likely a cell it to become…

Answer 13

Cancerous

Question 14

True or False:

One mutation is usually enough to cause cancer

Answer 14

Usually not

Question 15

Why does cancer risk increases with age?

Answer 15

Due to accumulating mutations

Question 16

Define:

Proto-oncogenes

Answer 16

Genes that are likely to lead to cancer if mutated

Question 17

Once mutated, genes correlated to cancer fall into what categories?

Answer 17

1. Oncogenes: ACCELERATE cancer growth
2. Tumor suppressors: STOP cancer growth

Question 18

Give examples of:

Oncogenes

Answer 18

1. Ras: Gene involved in cell signalling (controls cell growth, differentiation, and survival)
2. Myc expression: Leads to cell proliferation

Question 19

Give examples of:

Tumor suppressors

Answer 19

1. p53: Protects genomic stability and prevents mutations
2. BRCA1: Repairs DNA damage

Question 20

What can mutations in Ras result in?

Answer 20

Disruption of signals controlling cell growth, differentiation, and survival

Question 21

What can mutations in Myc expression lead to?

Answer 21

Over-expression results in cells proliferating out of control

Question 22

What can mutations in p53 lead to?

Answer 22

Loss of function, means other cancer-causing mutations are likely to arise

Question 23

What can BRCA1 mutations lead to?

Answer 23

Increase the risk of breast and ovarian cancer

Question 24

What types of mutations result in cancer?

Answer 24

1. Mutations in protein coding sequence
2. Gene amplification
3. Chromosomal rearrangement

Question 25

Describe:

Mutations in protein coding sequence in cancer

Answer 25

Results in hyperactive protein

Question 26

Describe:

Gene amplification in cancer

Answer 26

Results in too many copies of a gene which is translated into too much protein

Question 27

Describe:

Chromosomal rearrangement in cancer

Answer 27

A gene is placed under the control of the wrong transcription factors or is fused to an actively transcribed gene

Question 28

In the 1920s, what did Otto Warbug observe?

Answer 28

• Cancer cells use A LOT of glucose compared to the surrounding, non-cancerous tissue cells
• Cancer cells survived in the absence of oxygen as well

Question 29

Define:

Aerobic glycolysis

Answer 29

The glucose is metabolized into lactate even in the presence of oxygen

Question 30

Normal cells convert glycose into ATP via what two mechanisms?

Answer 30

1. Oxidative phosphorylation: In the PRESENCE of oxygen, 1 glucose = 36 ATP
2. Anaerobic respiration: In the ABSENCE of oxygen, 1 glucose = 2 ATP

Question 31

What is the “Warburg Effect”?

Answer 31

The speculation why cancer cells use a LESS efficient way of generating energy even in the presence of oxygen

Question 32

What are some speculated answers to the “Warburg Effect”?

Answer 32

1. Perhaps the cancer cells need other by-products obtained from anaerobic respiration
2. Perhaps cancer cells use anaerobic respiration because it is much faster than oxidative phosphorylation
3. Perhaps the mitochondria is damaged and the cancer cells CANNOT use oxidative phosphorylation
4. Ongoing research…