Cancer

What is Cancer?

a group of diseases capable of abnormal cell growth that has the potential to invade other parts of the body

Describe how cancer is different from normal cells

1. cancer cells do not die

2. therefore they infinitely replicate

3. they do not communicate w/ healthy cells

Metastasis

cancerous cells moving to other parts of the body away from the primary location

Malignant Tumour. What effect do they have to surrounding tissue?

Cancer

disrupt surrounding tissue

What is cancer in relation to genetics?

Cancer is a genetic disorder involving mutations in cells

Cancer is not _________, but certain _________ _________ can predispose one to cancer

1. inherited

2. inherited mutations

Cancer cell growth is…

uncontrolled

Oncogenesis

the development of a tumor

1. begins w/ loss of cell cycle control

2. tumor cells undergo further changes that allow them to invade and disrupt other tissues

Tumour

a swelling of tissue caused by uncontrollable cell growth due to the cell cycle losing control

The Cell Cycle

The repeating pattern of cell growth, mitosis and cell division

What are the 4 (5) phases of the cell cycle?

1. G₁

   1. G₀

2. S

3. G₂

4. M

When do chromosomes replicate?

S phase!

What happens in G₁?

interphase, gap before duplication

What happens in S?

DNA synthesis + chromosome duplication

What happens in G₂?

interphase, gap before mitosis

Cell Cycle Checkpoints

• control mechanisms to ensure proper progression

  • monitor major events in the cell cycle

    • e.g. growth (cell size), DNA replication, chromosome segregation

• Involve different CDK complexes (cyclin-dependent kinase)

What happens the cycle cannot progress to G2?

stops division

does not cause cancer

Would a mutation of p53 lead to cancer?

No.

1. cancer is multistep

2. cells gradually accumulate mutations in genes controlling

3. these are somatic mutations = mutations acquired during life, not inherited

Contact Inhibition

Which of the following is characteristic of cancer cells, but not of normal cells?

1. The ability to proliferate

2. Contact inhibition

3. Metastasis

4. All of the above

Metastasis

the ability to travel to other parts of the body away from the primary source of cells

1. all cells can grow and duplicate (proliferate)

2. this is actually a property of normal cells, where they stop dividing when touching neighbours

How does cancer usually develop?

1. It happens when cells can not progress to G2 phase.

2. It is caused by a mutation in p53.

3. It happens when a cell accumulates a series of somatic mutations.

4. It is caused by inheriting two recessive alleles, one from each parent

3. It happens when a cell accumulates a series of somatic mutations.

If one allele of p21 was mutated such that it could not interact with CDK, and the other allele was normal, could this lead to cancer?

1. No, because only one normal allele is required to perform the function

2. No, because this mutation would inhibit cell proliferation.

3. Yes, because mutations that alter, rather than completely eliminate, protein function are always dominant

4. Yes, because p21 is a proto-oncogene.

If both alleles for one of the "genes required for S phase" were mutated such that there was no gene expression at all from these alleles, could this lead to cancer? 

1. No, because these mutations would inhibit cell proliferation.

2. No, because these genes have no impact on the cell cycle.

3. Yes, because these genes are tumor-suppressor genes

4. Yes, because these genes are proto-oncogenes.

Would the mutation be dominant or recessive?

1. It would be recessive when inherited, but act dominantly in a cell.

2. It would be dominant.

3. It would be recessive.

4. It would be dominant when inherited, but act recessively in a cell.

When does Rb get phosphorylated?

1. When the cell experiences stress or DNA damage.

2. When the cell should undergo apoptosis.

3. When the cell should progress to S-phase.