BI236 Lecture Notes - Lecture 23: Tumor Suppressor Gene, Insertional Mutagenesis, Chromosomal Translocation
Document Summary
Tumor: mass of cells formed due to uncontrolled cell growth: benign tumors: confined; form single mass, rarely dangerous, malignant tumors (cancerous): capable of invading other tissues by metastasis. Enters bloodstream and spreading to distant parts of body. Eg: carcinomas (from epithelial cells); sarcomas (from connective tissue); lymphomas (from lymphatic cells) land leukemias (blood cells) 2 main types of genes show altered activities in cancer cells: oncogenes, tumor suppressor genes. In normal skin growth: one cell differentiates and the other remains in basal layer and retains ability to divide: no increase in # of dividing cells. Tumor growth: balance b/w cell division & cell differentiation is disrupted: some divisions give rise to cells that both continue to divide. Epithelial cancers account for 90% of human malignancies. Insensitive to population density: grow beyond monolayer: lose contact inhibition. Cancer cells are immortalize by maintaining telomere length: normal cells divide limited # of times in culture; cancer cells . forever.
