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Unformatted text preview: Chapter 18 Cell Cycle Regulation and Cancer Cancer is a genetic disease- what is cancer? o cancer large number of complex diseases that behave differently depending upon the cell types from which they originate vary in their ages of onset, growth rates, invasiveness, prognoses, and responsiveness to treatments o cancer cells share two fundamental properties cell proliferation abnormal cell growth and division metastasis abnormalities in the normal restraints that keep cells from spreading and invading other parts of the body o two types of growth masses benign tumor cell simply loses genetic control over cell growth • often be removed by surgery and usually causes no serious harm malignant tumor cells in the tumor acquire ability to break loose, enter the bloodstream, invade other tissues, and form secondary tumors • difficult to treat, may become life threatening- clonal origin of cancer cells o all cancer cells in primary and secondary tumors are clonal – originated from common ancestral cell that accumulated numerous specific mutations o numerous data support this idea burkitt’s lymphoma show reciprocal translocations between chromosome 8 and chromosomes 2, 14, or 22 pattern of X-chromosomes inactivation – all cancer cells within a tumor, and within all primary and metastatic tumors in one female individual, contain same inactivated X-chromosome- cancer as a multistep process, requiring multiple mutations o single mutation is not sufficient to transform a normal cell into a tumor- forming malignant cell carcinogens cancer-causing agents • exposure to these and the relations to the appearance of cancer cancer cells contain genetic defects affecting genomic stability and DNA repair- cancer cells show higher than normal rates of mutation, chromosomal abnormalities, and genomic instability o mutator phenotype high level of genomic instability seen in cancer cells manifests itself in presence of gross defects such as translocations, aneuploidy, chromosome loss, DNA amplification, and chromosome deletions cancer cell cultures grown in lab show great deal •...
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