8.2.3 Cancer: When Mitosis Goes Unchecked

Question 1

cancer

Answer 1

• are cells that have an unregulated cell cycle. Cancer cells are immortal, do not need to be anchored in order
  to grow, and do not exhibit density-dependent inhibition

Question 2

oncogene

Answer 2

• a cancer-causing gene found in viruses and in genomes of organisms.

Question 3

proto-oncogene

Answer 3

• a regularly occurring gene that is involved in cell cycle regulation and that has the potential to become
  an oncogene if altered. A proto-oncogene can be switched to an oncogene by several mechanisms including the transposition of the gene to a different promoter, the amplification of a gene, and gene mutation
• can be switched to oncogenes by a variety
  of methods:
  · If the proto-oncogene is moved to a more active promoter by transposition, there could be a higher production of regulatory proteins that could, in turn, allow the cell to divide out of control.
  · Gene amplification causes more gene expression. If there is an excess of a regulatory protein, then the cell cycle could continue out of control.
  · If the protein product of a mutated proto-oncogene gene is changed in such a way that it is unable to be
  degraded, then the cell cycle could continue.

Question 4

Peyton Rous

Answer 4

• In 1911 Peyton Rous discovered that viruses could cause cancer. Viruses are able to inject their genetic material into a host cell. Some viruses multiply by causing the host cell to replicate uncontrollably.

Question 5

A major difference between cancer cells and normal cells is that

Answer 5

• cancer cells will not stop growing when they are crowded

Question 6

What is metastasis?

Answer 6

• The migration of cancer cells from their origin

Question 7

What is the difference between an oncogene and a proto-oncogene?

Answer 7

• An oncogene is a cancer-causing gene, while a proto-oncogene is a normally occurring gene that does not cause cancer but could

Question 8

Which of the following statements is false?

Answer 8

• Proto-oncogenes result from viral infections

Question 9

A / An __________ mutates and becomes a / an __________, which causes cancer.

Answer 9

• proto-oncogene; oncogene