8. Features of cancer cells cell shape is easily distinguished from normal, healthy cells cancerous cells lose their attachment to neighboring cells cancer cells may have an unusual # of chromosomes cancer cells can go on dividing indefinitely , if they have an unlimited supply of nutrients they are said to be “immortal” metabolism may be drastically altered and the cell stops functioning in a constructive way
9. Oncogenesis, proto-oncogenes and tumor suppressor genes There are two types of genes necessary for normal control of cell division: 1. proto-oncogenes (start cell division and are essential for normal cell development) 2. tumor suppressor genes (switch off cell division) Oncogenes: these arise when these cell cycle control genes become mutated -- these mutations lead to uncontrolled cell division Ex: many cancers are initiated when there are mutations in tumor-suppressor genes p53 : this tumor suppressor gene encodes for a protein that halts the cell cycle so that DNA can be repaired before division