Reading 14 Flashcards
What is the meaning of benign?
Tumor cells that remain localized
What is the meaning of malignant?
Tumor cells that invade other tissues
What are three observations that suggest cancer results from genetic damage, or that genes play a role in cancer, also known as the “genetic theory of cancer”?
- Many agents cause both mutations and cancer, such as radiation and chemicals
- Some cancers are consistently associated with particular chromosome abnormalities
-some specific cancers tend to run in the family
What are some of the problems with the genetic theory of cancer as presented?
- If cancer is inherited then every cell should inherit the cancer causing gene and therefore, every cell should become cancerous
- In cancer can run in the family it only occurs in certain tissues and at an old age
-many cancers don’t run in families and are often random
What is meant by “clonal evolution” of tumors?
Tumor cells receive more mutations that allow them to become more aggressive and spread
What are some environmental factors that contribute to cancer?
Tobacco, alcohol, UV radiation, and other chemicals such as benzene
What is an oncogene? Who is responsible for discovery of the first known oncogene?
- Multiplied copies of dominant acting stimulatory genes that cause cancer
-Peyton Rous
Why are oncogenes usually dominant in their action, whereas tumor-suppressor genes are recessive?
- Tumor suppressor genes are more difficult to find that oncogenes because they inhibit cancer and are recessive
-Both alleles must be mutated before the inhibition of cell division is removed
How can aberrant activation of the enzyme telomerase contribute to the progression of cancer?
it allows the cell to divide indefinitely
How can a retrovirus cause cancer?
Retroviruses sometimes cause cancer by mutating and rearranging host genes and converting proto-oncogenes into oncogenes
