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The Cell Cycle and Cancer The Stages of the Cell Cycle There are several factors that regulate the cell cycle and assure a cell divides correctly. 1.Before a cell divides, the DNA is checked to make sure it has replicated correctly. (If DNA does not copy itself correctly, a gene mutation occurs. 2. Chemical Signals tell a cell when to start and stop dividing. Neighboring cells communicate with dividing cells to regulate their growth also. Cancer is a disease of the cell cycle. Some of the body’s cells divide uncontrollably and tumors form. Tumor in Colon Tumors in Liver DNA mutations disrupt the cell cycle. Mutations may be caused by: 1. radiation 2. smoking 3. pollutants 4. chemicals 5. viruses While normal cells will stop dividing if there is a mutation in the DNA, cancer cells will continue to divide with mutation. Cell Suicide or Apoptosis Cell damage— no repair First mutation Second mutation Third mutation Fourth or later mutation Uncontrolled growth Due to DNA mutations, cancer cells ignore the chemical signals that start and stop the cell cycle. Due to DNA mutations, cancer cells cannot communicate with neighboring cells. Cells continue to grow and form tumors. Skin cancer ABCD of Cancer Regions of Highest Incidence U.K.: UK: Lung Lung cancer cancer Regions of Highest Incidence JAPAN: Stomach cancer CHINA: Liver cancer AUSTRALIA: Skin cancer Cancer by State US: Colon cancer CANADA: Leukemia BRAZIL: Cervical cancer Mitosis and Cancer 1. Typically, cell division is controlled by genes in the cell, contact with other cells, and available nutrients in the environment. 2. Cancer is a class of diseases characterized by uncontrolled cell division and the ability of these cells to invade other tissues. How Cancer Develops Treating Cancers Cancer treatments include surgery, chemotherapy, radiation, or lasers. SUMMARY Normal Cell Division DNA is replicated properly. 2. Chemical signals start and stop the cell cycle. 3. Cells communicate with each other so they don’t become overcrowded. 1. Cancer Cells Mutations occur in the DNA when it is replicated. 2. Chemical signals that start and stop the cell cycle are ignored. 3. Cells do not communicate with each other and tumors form. 1. Vocabulary cancer: term used to indicate a disease characterized by abnormal cell growth mutagen: environmental factor that causes mutations carcinogen: cancer-causing agent tumor: mass of growing tissue benign: does NOT invade surrounding cells malignant: spreads into nearby tissues metastasis: spread of malignant cells oncogene: gene that causes cancerous growth