Cancer Genetics Flashcards
(18 cards)
What are the 4 main types of cancer?
- Leukemias
- Lymphomas
- Carcinomas
- Sarcomas
Be able to distinguish between the 4 types of cancer and give an example of each (Sarcoma)
Sarcoma
- Solid tumors from embryonic mesoderm tissue
- Ex. bone, cartilage, muscle, fat
- 1.9% of cancers
Be able to distinguish between the 4 types of cancer and give an example of each (Carcinoma)
Carcinoma
- Solid tumor from epithelial tissue (body surface coverings and derivatives)
- Ex. skin, breast, respiratory, colon, urinary
- 85.3% of cancers
Be able to distinguish between the 4 types of cancer and give an example of each (Lymphoma)
Lymphoma
- Abnormally large numbers of lymphocytes (type of WBC) made by spleen and lymph nodes
- Ex. Hodgkin Disease
- 5.4% of cancers
Be able to distinguish between the 4 types of cancer and give an example of each (Leukemia)
Leukemia
- Abnormally large number of leukocytes (WBCs) made by bone marrow
- Common in children, but can occur in adults
- 3.4% of cancers
Define each of the following characteristics of cancer: Anaplasia
Anaplasia: a characteristic of cancer: structure/function of cell is undifferentiated.
Define each of the following characteristics of cancer: Hyperplasia
Hyperplasia: a characteristic of cancer: uncontrolled cell division.
Define each of the following characteristics of cancer: Metastasis
Metastasis: a characteristic of cancer: ability to move to and establish tumors at other sites in body.
What is an oncogene? Give an example and describe a situation in which this oncogene contributes to cancer.
- An oncogene is a mutation in a proto-oncogene or in its regulation (normally promote cell division, but must be activated to regulate properly). The oncogene allows uncontrolled cell division.
What is a tumor suppressor gene? Give an example and describe a situation in which this tumor suppressor gene contributes to cancer.
Tumor suppressor genes: prevent bad cells from dividing - recessive-acting mutation: both copies must be mutated to get tumor (or mutation in one and deletion in one).
ex. p53
Compare and contrast the action of tumor suppressor genes and oncogenes.
Oncogenes allow good cells to divide.
Tumor suppressor genes prevent bad cells from dividing.
Only need mutation in 1 copy of a proto-oncogene to get tumor (dominant mutation - heterozygous) whereas in tumor-suppressor gene, both copies must be mutated to get tumor (recessive mutation - homozygous).
How do tumor suppressor genes and oncogenes relate to parts of a car?
Proto-oncogenes are like the gas petal. A defective oncogene would be like a gas petal stuck on even when no foot is pushing it down.
Tumor suppressor genes are like the brakes.
What types of cancers are associated with the RB, BRCA1 and BRCA2 genes? Are these genes oncogenes or tumor suppressor genes?
- RB: Retinoblastoma - tumor suppressor genes
40% of cases are inherited (1 bad gene present in the zygote).
Knudson’s two hit hypothesis - both copies have to be defective in same cell to allow tumor to develop. - BRCA1 and BRCA2 - tumor suppressor genes
Account for about 10% of breast cancers (BRCA1 associated with half of hereditary breast cancers; 90% of women with mutation in BRCA1 get breast cancer).
Also ovarian cancer.
Men have increased risk of breast cancer and prostate cancer with BRCA2.
Discuss the role of p53 in cancers. Is it a tumor suppressor gene or oncogene? Why is this gene like the fork in the road?
p53: chromosome 17: tumor suppressor gene.
- Functions at G1 checkpoint
- Mutated form seen in diverse cancer types: colon, lung, breast, brain and is found in altered form of 50% of human tumors.
- Normally, if DNA is damaged, p53 delays cell division until damage is repaired or programs cell to die.
- If p53 not working properly, cell division occurs even though DNA is damaged and occurs in unregulated manner.
- Like a fork in the road because it has to decide whether the DNA in the cell will be repaired or the cell will self-destruct.
What is retinoblastoma?
Retinoblastoma is a rapidly developing cancer that develops from the immature cells of a retina, the light-detecting tissue of the eye and is the most common malignant tumor of the eye in children.
Describe what is meant by the two-hit hypothesis for some cancer types. Give an example of a cancer type and the gene(s) involved that operate this way
Knudson’s two hit hypothesis: both copies have to be defective in same cell to allow tumor to develop.
Retinoblastoma - RB gene
Give an example of a cancer type that is due to a reciprocal translocation
Burkitt’s Lymphoma
Chronic Myelogenous Leukemia
Give an example of a cancer type that is due to a series of tumor suppressor and oncogene mutations
Colon cancer
