Chapter 5 (Part 2) Flashcards

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1
Q

the cell cycle is controlled by…

A

checkpoints

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2
Q

what is apoptosis?

A

programmed cell death

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3
Q

mutations are either _______ or ________

A

repaired or undergo apoptosis

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4
Q

3 principal checkpoints control the cycle in eukaryotes

A

G1, G2, and M checkpoints

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5
Q

G1 checkpoint

A
  • 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
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6
Q

G2 checkpoint

A
  • Determine if mutations occurred in DNA replication
  • Repair enzymes available to correct mutations.
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7
Q

M checkpoint

A

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

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8
Q

Cancer results from…

A

mutated cells growing unregulated by growth checkpoints

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9
Q

oncology

A

the study of cancer

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10
Q

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

A

tumour

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11
Q

Benign tumours

A

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

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12
Q

Malignant tumours

A

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

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13
Q

new tumours are called

A

metastases ( or secondary tumours)

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14
Q

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

A

Proto-oncogenes, tumour-suppressor genes

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15
Q

Proto-oncogenes

A

*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.

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16
Q

tumour-suppressor genes

A
  • 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
17
Q

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

A
  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)
18
Q

cancer can result from…

A

damaged genes failing to control cell division

19
Q

the tumour suppressor gene p53 affects what checkpoint?

A

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

20
Q

if mutation is detected, tumour-suppressor gene can…

A

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

21
Q

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

A

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

22
Q

less exposure to mutagens =

A

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

23
Q

cancer is caused by

A

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

24
Q

cause or orgin of damaged genes

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