BIO 111 Lecture 20: BIO 111 11/23/16
Document Summary
~80% of cancers related to mutagen exposure. Change gene expression uncontrolled cell division. Initially benign tumor, can become malignant with accumulation of more mutations. Benign tumors don"t spread or involve nearby tissues. Malignant tumors are cancerous; have more mutations and loss of cell regulation. Now more likely to spread & affects nearby tissues. Growth factors bind to receptors on the cell. Activate transcription factors to regulate gene activity. Signal transducers may be stuck in an activated state. Transcription factors may be produced, even if preceding steps are absent. Proto-oncogenes regulate cell division by growth factors. Can get stuck on due to mutations. Important in preventing cancer; they stop cell division. But if these get mutated, can get stuck turned off . The accelerator must get stuck and the brakes must fail . Cancer from an accumulation of mutations. ~50% cancers associated with defect in p53. Resulting protein stops cell cycle and repairs damage.
