Chapter 5 (Part 2)

Question 1

the cell cycle is controlled by…

Answer 1

checkpoints

Question 2

what is apoptosis?

Answer 2

programmed cell death

Question 3

mutations are either _______ or ________

Answer 3

repaired or undergo apoptosis

Question 4

3 principal checkpoints control the cycle in eukaryotes

Answer 4

G1, G2, and M checkpoints

Question 5

G1 checkpoint

Answer 5

• Determines whether the cell should enter S phase for DNA replication and cell division
• Some cells never pass this point and are said to be in G0

Question 6

G2 checkpoint

Answer 6

• Determine if mutations occurred in DNA replication
• Repair enzymes available to correct mutations.

Question 7

M checkpoint

Answer 7

Occurs during metaphase and determines whether mitosis should proceed. Triggers exit from M phase
and entry into G1 phase

Question 8

Cancer results from…

Answer 8

mutated cells growing unregulated by growth checkpoints

Question 9

oncology

Answer 9

the study of cancer

Question 10

the result of cancer is a growing cluster of cells is called a

Answer 10

tumour

Question 11

Benign tumours

Answer 11

surrounded by a smooth layer of cells and do not spread to other areas

Question 12

Malignant tumours

Answer 12

have irregular cell borders, are not encapsulated, and are invasive. cells leave and spread to other areas forming new tumours

Question 13

new tumours are called

Answer 13

metastases ( or secondary tumours)

Question 14

what are the two general classes of genes that are usually involved in cancer?

Answer 14

Proto-oncogenes, tumour-suppressor genes

Question 15

Proto-oncogenes

Answer 15

*These genes encode proteins that stimulate the cell cycle.
*Mutations to these genes can cause cells to divide excessively.
*When mutated, they are called oncogenes.

Question 16

tumour-suppressor genes

Answer 16

• Encode proteins that normally arrest the cell cycle (at the three checkpoints).
• When mutated, these genes are not able to control rate of cell division.
• p53 is the most famous example of this gene type

Question 17

cancer may develop if any of these types of genes are mutated

Answer 17

1. Genes regulating the cell cycle: such as proto-oncogenes and tumor-suppressor genes
2. DNA repair enzymes (→ more mutations)
3. Genes involved in apoptosis (→ cancer cells live on)
4. Genes that regulate the immune response (→ cancer cells escape NK cells)
5. Genes that increase angiogenesis (→ more nutrients for growth of the tumour)

Question 18

cancer can result from…

Answer 18

damaged genes failing to control cell division

Question 19

the tumour suppressor gene p53 affects what checkpoint?

Answer 19

G1
- usually detects abnormal DNA
- can stop the cycle and recruit DNA repair enzymes.
- if cannot be fixed, cell goes into apoptosis.

Question 20

if mutation is detected, tumour-suppressor gene can…

Answer 20

stop the cell cycle and direct repair enzymes to the mutation. If that fails, they can trigger apoptosis

Question 21

What does the immune system do when a mutated cell continues to divide unregulated?

Answer 21

the immune system has natural killer cells and cytotoxic T-cells that can destroy cancerous cells.

Question 22

less exposure to mutagens =

Answer 22

less mutations to take care of which also means less chance for cancer.

Question 23

cancer is caused by

Answer 23

damaged genes in stomatic tissue that fail to properly control the cell cycle

Question 24

cause or orgin of damaged genes

Answer 24

• Familial or Inherited Genetic Mutations (5-10%)
• Genetic Mutations from Environmental Factors (90-95%)