Transcript BBM 24
The body is a society whose members are cells, organized into tissues Cancer cells grow when they should not Cancer cells invade other tissues These are the behaviors of free growing cells, like bacteria Types of Tumors Benign Grow slowly as a single mass Malignant Grow rapidly and invade other tissues 90% of mutagens are carcinogens An environmental insult leads to DNA damage This results in a mutation…a change in DNA sequence This mutation often alters cell proliferation The cancer cells grows out of control One mutation alone does not lead to cancer There are 1016 cell divisions in a human lifetime Rate of spontaneous mutation = 10-6 /gene/division Every gene will have 1010 mutations in an average lifetime Cancer cells develop slowly Smoking leads to lung cancer 10 to 20 years Radiation exposure (the bomb) causes leukemias 5 to 8 years Cancer as a function of age Genes implicated in cancer • Oncogenes • Tumor supressor genes • DNA repair genes Genes supressores de tumores Estes genes inibem normalmente o crescimento, a diferenciação ou a divisão celulares A mutação provoca uma perda de função Ambas as cópias do gene são mutadas (recessivos) Examplo: gene Rb Mutações no Rb provocam retinoblastomas Mutações no gene Rb podem conduzir ao retinoblastoma X X X XX X X XX O p53 é um gene supressor de tumores Most people with an alelle of p53 mutated develops cancer