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genetics cancer
genetics exam 3
| Question | Answer |
|---|---|
| The ABL fusion gene is seen in? | about 95% of cases of CML |
| What is a fusion gene? | 2 genes merge together due to chromosomal rearrangement |
| What happens to the ABL fusion gene in CML? | ABL gene (9) merges with BCR gene (22)-> forms Philadelphia chromosome |
| What is the Philadelphia chromosome? | t(9;22) (q34;q11) reciprocal translocation |
| Two main types of genes involved in cancer | tumor suppressor, oncogene |
| which one of the two main types of genes involved in cancer is the brake? | tumor suppressor |
| What happens when the tumor suppressor gene is mutated or inactivated? | cells are unable to respond normally to cell-cycle checkpoints or are unable to undergo programmed cell death if damage is extensive |
| What does a mutation or inactivation of the tumor suppressor gene eventually lead to? | accumulation of more mutations and development of cancer |
| tumor suppressor gene | gene whose products normally regulate cell cycle checkpoints or initiate the process of apoptosis in all cells; inhibit cellular proliferation |
| is the tumor suppressive gene recessive or dominant at the cellular level? | recessive |
| What does it mean that the tumor suppressor gene is recessive at the cellular level? | both copies of a specific TSG must be mutated to cause a change in cell growth-> loss of function mutation |
| Do heterozygous cells of tumor suppressor genes develop into cancer? | no |
| are tumor suppressor genes recessive or dominant at the individual level? | dominant |
| What does it mean that tumor suppressor genes are dominant at the individual level? | heterozygotes can express the phenotype if they have inherited 1 mutation and acquired another (2nd hit) |
| Most genes associated with inherited cancer syndromes are? | tumor supressor genes |
| are most mutations in tumor suppressor genes inherited? | no |
| Which one of the two main genes involved in cancer is the accelerator? | oncogene |
| What happens when normal cells become quiescent and cease division? | they repress the expression of pro-oncogene or modify the activity of their products |
| oncogene | when a proto-oncogene is mutated or abnormally expressed and contributes to the development of cancer; activate cellular proliferation |
| proto-concogenes | normal genes that encode products important for cell growth and division |
| examples of proto-oncogenes | transcription factors, signal transduction molecules, cell cycle regulators |
| are oncogenes recessive or dominant at the cellular level? | dominant |
| what does it mean that oncogenes are dominant at the cellular level? | having a mutation in just 1 allele is enough to contribute to development of cancer due to unregulated cell cycle growth |
| what kind of mutation is an oncogene? | gain of function |
| a heterozygote oncogene cell develops into? | tumors |
| number of hits required for TSGs | 2 |
| number of hits required for oncogenes | 1 |
| are oncogenes inherited mutations? | no |
| TP53 is responsible for? | DNA repair pathways as well as checkpoint regulation and cell apoptosis |
| what is TP53 known as? | "guardian of the genome" |
| expression of TP53 increases in response to? | cell damage |
| depending on the level of DNA damage, p53 activates genes involved in? | DNA repair or apoptosis |
| cells lacking functional p53 are unable to? | arrest at cell cycle checkpoints or to enter apoptosis in response to DNA damage |
| what happens when cells lacking function p53 are unable to arrest at cell cycle checkpoints or to enter apoptosis in response to DNA damage? | cells move through the cell regardless of the condition of DNA |
| what happens when cells move through the cell regardless of the condition of DNA? | high mutation rates and accumulation of many mutations |
| what is the most frequently mutated gene in human cancer? | TP53 |
| TP53 is mutated in more than what percent of human tumors? | 50% |
| in addition to the checkpoints, regulation of cell cycle progress is mediated by? | cyclins and cyclin dependent kinases |
| what do cyclin dependent kinases regulate? | synthesis and destruction of cyclin proteins |
| mutation of misexpression of any of the genes controlling the cell cycle can contribute to? | the development of cancer |
| mutated genes controlling G1/S or G2/M checkpoints or those controlling cyclins may allow cells to? | continue to grow and divide without repairing DNA damage |
| cell controls progress through cell cycle by means of two classes of proteins | cyclins and cyclin dependent kinases |
| CDK/ cyclin complex selectively... | phosphorylates and activates proteins to bring about necessary changes for cell cycle to continue |
| cyclins | levels rise and fall to turn CDKs on at the right time |
| two hit hypothesis | at least one other somatic variant in the other copy of the gene must occur to drive a cell forward toward tumorigenesis |
| inherited cancer | germline; multiple family members with same, related, rare or bilateral cancers |
| inherited cancers are usually? | autosomal dominant inheritance of 1 mutation |
| inherited cancer traits | young age at onset, history of individual who developed 2+ separate or multifactorial cancers |
| inherited/ germ line cancer is passed from? | parent or child through egg or sperm |
| inherited/ germ line cancer is present in? | every cell of the body |
| most inherited cancer susceptibility alleles occur in? | tumor suppressor genes |
| are most inherited cancer susceptibility alleles sufficient in themselves to trigger cancer development? | no |
| genetic/ somatic cancers occur during? | the person's lifetimes |
| genetic/ somatic cancers are not present in? | egg or sperm |
| mutations that occur in one cell of genetic/somatic cancers are passed on to? | the progeny cells |
| what is more common inherited or genetic cancer mutations? | genetic |
| progression from early mutation to metastasis | the continuing change over time of a cancer cell population causing them to become "more malignant," more aggressive and less normal in appearance, function, and growth regulation |
| what happens as cancer cells progress from early mutation to metastasis? | increased growth rate, increased invasiveness, biochemical changes, morphological changes, metastasis |
Created by:
camrynfoster