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CANCER AND THE CELL CYCLE Mrs. Gamari No matter how many new homes a builder builds, even if building the same design, the builder and the crew rely on the blueprint instructions for their construction. Similarly, cells rely on instructions for going through the cell cycle. NORMAL CELL DIVISION Growth should balance (apoptosis) old cell death CHECKPOINTS Cyclins – proteins that bind to enzymes (cyclin-dependent kinases) in the stages of interphase and mitosis to start various activities of the cell cycle. Different cyclin/CDK combinations control different activities Start of the cell cycle DNA replication Protein synthesis Nuclear division End of the cell cycle CELL GROWTH Epithelial layers of skin Basal layer cells should balance outer surface cells CANCER Uncontrolled growth and division of cells Results when cell cycle checkpoints fail Cancerous cells can kill an organism by crowding out normal cells, impairing normal tissue function. TUMOR FORMATION Cancer cells lack “contact-inhibition” Basal cell layer outnumbers cells in surrounding areas. WHY MIGHT THE CHECKPOINTS FAIL? Cells can become “abnormal” in a variety of ways. Carcinogens = cancer-causing substances Toxins / Chemicals UV Radiation Could be influenced by genes OR environment Diet/Lifestyle Viruses Family history ALL OF THESE SOMEHOW DAMAGE THE PART OF DNA THAT REGULATES CELL DIVISION WHAT IS A MUTATION? GENES THAT HELP REGULATE CELL DIVISION Tumor Suppressor Genes DAMAGE Proto-oncogenes DAMAGE DIFFERENTIATION CANCER CELL CHARACTERISTICS Cancer cells are usually irregularly shaped. Cancer cells are more simplistic or undifferentiated. HEALTHY CELL FUNCTIONS Make proteins or “worker molecules” required by the body Communicate with other cells by sending signals and messages Make their own energy using oxygen Divide to make new cells Grow in a controlled fashion and know where they belong in the body Die after a specific number of divisions (apoptosis) CANCER CELL FUNCTIONS (OR LACK THEREOF) Proteins can be missing, misshaped or in unnecessary amounts Messages or signals used for communication are missing or changed Energy is made using sugar (usually just glycolysis- not aerobic respiration) Growth is not regulated so the cancer cells grow out of control (dysplasia). Cells can go places in the body where they do not belong An “immortal” nature allows the cancer cells to live longer than normal GOOD CELLS GONE BAD! Each group provided with a “normal cell” and a “cancer cell”. Examine the contents of the cells and determine what each object symbolizes. Fill out worksheet and answer analysis questions.