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Genetics Chapter 16
Cancer Genetics
| Term | Definition |
|---|---|
| cancer is a group of disease characterized by what? | cell proliferation |
| normal cells grow, divide, mature, and die in response to a complex set of _________ and _________ signals | internal and external |
| in a ______cell, one or more of the signals has been disrupted which causes the cell to proliferate at an abnormally high rate | cancer |
| as cancer cells lose their response to the normal controls, they gradually lose their regular shape and boundaries, eventually forming a distinct mass of abnormal cells called a ______ | tumor |
| if the cells of the tumor remain localized, the tumor is said to be _______ | benign |
| if the cells invade other tissues, the tumor is said to be _________ | malignant |
| cells that travel to other sites in the body, where they establish secondary tumors, have undergone __________ | metastasis |
| cancer arises as a results of fundamental defects in the regulation of _____ _______ | cell division |
| cancer is fundamentally a ________ disease | genetic |
| early observations suggested cancer might result from genetic damage: first, many agents such as ________ ________ and chemicals that cause mutations, also cause cancer | ionizing radiation |
| early observations suggested cancer might result from genetic damage: second, some cancers are consistently associated with particular __________abnormalties | chromosome |
| early observations suggested cancer might result from genetic damage: third, some specific types of cancers tend to run in __________ | families |
| who proposed a model to explain the genetic basis of cancer? | Knudson |
| knudson proposed that cancer is the result of a _______ process that requires several mutations | multistep |
| knudson's genetic theory for cancer has been confirmed by the identification of genes that, when _______, cause cancer | mutated |
| _______ _________ is the process by which mutations that enhance the ability of cells to proliferate predominate in a clone of cells, allowing the clone to become increasingly rapid in growth and increasingly aggressive in proliferation properties | clonal evolution |
| the rate of clonal evidence depends on the frequency with which new __________ arise | mutations |
| mutations in genes that affect chromosome ___________ also may contribute to the clonal evolution of tumors | segregation |
| although cancer is a genetic disease, most cancers are not inherited, and many cancers are influenced by ____________ factors | environmental |
| the role of environmental factors in cancer is suggested by what? | differences in the incidence of specific cancers throughout the world |
| studies show that migrant populations typically take on the cancer incidence of their ____ country | host |
| most environment factors (smoking, UV, etc) associated with cancer cause _________ mutations that stimulate cell division or affect the process of cancer | somatic |
| environmental factors may interact with genetic ____________ to cancer | predispositions |
| the signals that regulate cell division fall into two basic types: molecules that __________ cell division and those that _________ it | stimulate, inhibit |
| a stimulatory gene can be made hyperactive or active at inappropriate times. mutations in stimulatory genes are usually __________ | dominant |
| mutated copies of dominant-acting stimulatory genes that cause cancer are termed _________ | oncogenes |
| cell division may also be stimulated when inhibitory genes are made _______ | inactive |
| mutate inhibitory genes generally have recessive effects because both copies must be ________to remove all inhibition | mutated |
| inhibitory genes in cancer are termed ______-_________ _____ | tumor-suppressor genes |
| although oncogens or mutated tumor-suppressor genes or both are required to produce cancer, mutations in DNA-____ genes can increase the likelihood of acquiring mutations in these genes | repair |
| _________ were the first cancer-causing genes to be identified by pnysician Rous (hen with tumor) | oncogenes |
| ________ and ________ used probes for viral oncogenes to search for related sequences in normal cells. | Bishop and Varmus |
| they discovered that the genomes of all normal cells carry DNA sequences that are closely related to viral _________. These cellular genes are called ____-________ | oncogenes, proto-oncogenes |
| proto-oncogenes are responsible for what? | basic cellular functions in normal cells |
| when proto-oncogenes are mutated, they become _________ that contribute to the development of cancer | oncogenes |
| because proto-oncogenes are more likely to undergo mutation or recombination within a virus, _____ infection is often associated with cancer | viral |
| tumor-________ genes are more difficult to identify because they inhibit cancer and are recessive | suppressor |
| inactivation or loss of the one remaining allele is all that is required to completely eliminate the tumor-suppressor product. Inactivation of the remaining wild-type allele in heterozygotes is referred to as the _____ ___ ________ | loss of heterozygosity (often caused by deletion) |
| progression through the cell cycle is controlled at __________ | checkpoints |
| what are these checkpoints regulated by? | interactions between cyclins and cyclin-dependent kinases (CDKs) |
| cyclin-dependent kinases (CDKs) are ________ that add phosphate groups to other proteins. sometimes it activates the protein and other times it inactivates the protein | enzymes |
| CDKs are functional only when they associate with another protein called _______ | cyclin |
| many cancers are caused by defects in the cell cycle's ___________ machinery | regulatory |
| some proto-oncogenes and tumor-suppressor genes have roles in _________, a process of programmed cell death in which the cell's DNA is degrades, its nucleus/cytoplasm shrink, and cell undergoes phagocytosis by other cells w/o leakage of contents | apoptosis |
| cells have the ability to assess themselves and when they are abnormal or damaged, they normally undergo _________ | apoptosis |
| mutations in genes that encode components of DNA-______ systems are often associated with cancer | repair |
| these mutations increase the rate at which mutations are retained. What is the result? | an increased number of mutations in proto-oncogenes, tumor-suppressor genes, and other genes that contribute to cell proliferation |
| another factor that can contribute to the progression of cancer is the inappropriate activation of an enzyme called __________ | telomerase |
| mutations that allow telomerase to be expressed in ________ cells and those that affect vascularization and metastasis also can contribute to cancer progression | somatic |
| chromosome ___________ is a general feature of cancer cells, causing them to accumulate chromosome mutations, which then affect individual genes that may contribute to cancer | instability |
| mutations in some genes cause or allow the missegregation of chomosomes, leading to _______ that can contribute to cancer | aneuploidy |
| most tumors contain cells with ___________ mutations | chromosome (including deletions, inversions,and translocations) |
| deletions can eliminate or inactivate genes that control the _____ ________ | cell cycle |
| __________ and ______________ can cause breaks in genes that support tumors, fuse genes to produce cancer-causing proteins, or move genes to new locations, where they are under the influence of different regulatory sequences | inversions and translocations |
| viruses are associated with some cancers. They contribute to cell proliferation by what two ways? | mutating/rearranging host genes or by altering the expression of host genes |
| colorectal cancer offers a model system for understanding tumor ____________ in humans | progression |
| colorectal cancers arise in the cells ligning the ______ and _______ | colon and rectum |
| initial mutations stimulate cell division, leading the what? | small benign polyp (small growth) |
| additional mutations allow the polyp to do what? | enlarge, invade the muscle layer of the gut, and eventually spread to other sites |
| mutations in particular genes affect _________ stage of this progression | different |
Created by:
cmccartney2