Presentation on theme: "Cancer. Regulation of Cell Division Two sets of genes control cell division. –Proto-oncogenes. Code for proteins that promote the cell cycle and prevent."— Presentation transcript:
Regulation of Cell Division Two sets of genes control cell division. –Proto-oncogenes. Code for proteins that promote the cell cycle and prevent cell death. –Tumor suppressor genes. Code for proteins that stop the cell cycle and promote cell death.
Replicative Potential After cells become fully differentiated they can no longer divide. –Chromosomes in human cells end with repetitive DNA sequences, telomeres. Telomeres get shorter after each cell cycle.
Cancer Cells Carcinogenesis - Development of cancer. –Cancer is a genetic disease requiring at least ten mutations, each propelling cells toward tumor development. Each tumor is composed of cells that are experiencing uncontrolled growth. –Cancer cells are nonspecialized and do not contribute to body functioning.
Cancer Cell Characteristics Genetically unstable. Not differentiated - Do not adhere to other cells. Insensitive to inhibitory growth signals. No apoptosis (cell death) when DNA repair fails. Unlimited number of cell cycles. Induce and sustain angiogenesis (formation of new blood vessels – get O 2 to middle of tumor). Invade and metastasize.
Regulation of Cell Cycle Approximately 100 oncogenes (cancer- causing genes) discovered that can cause increased cell growth and lead to tumors. –Most frequent are in Ras gene family (proteins that promote mitosis & cell division). Cancer cells no longer respond to inhibitory growth factors (factors that STOP division). Tumor suppressor genes undergo mutations. –Approximately half-dozen identified.
Faces of Cancer: 1 in 3 people will develop cancer 25% of them will die from cancer