Cell Cycle and Cancer Biology I 2015 2016

Cell Cycle and Cancer Biology I 2015 -2016 Mrs. Thompson

Cell Cycle Checkpoints • Cell Cycle Checkpoint: critical control point where stop and go signals can regulate the cycle ▫ Typically in the “off” position ▫ Specific stimuli needed to start the cycle �Growth Factors: groups of proteins that stimulate cell division

Cell Cycle Checkpoints • Three checkpoints: ▫ G 1 Checkpoint: �G 1 task: cell growth �G 1 checkpoint: ▫ Checks for damaged DNA ▫ Makes sure everything required for replication is available ▫ G 2 Checkpoint: checks for damaged DNA and ensures all DNA was replicated ▫ M Checkpoint: ensures sister chromatids are attached correctly to the spindle fibers

Cell Cycle Checkpoints • Three checkpoints: ▫ G 1 Checkpoint: ▫ S/G 2 Checkpoint: checks for damaged DNA and ensures all DNA was replicated �S task: synthesize (replicate DNA) �S/G 2 Checkpoint goal: �Checks to make sure all the DNA was replicated �Checks for mutations in the DNA

Cell Cycle Checkpoints • Three checkpoints: ▫ G 1 Checkpoint: ▫ S/G 2 Checkpoint: ▫ M Checkpoint: ensures sister chromatids are attached correctly to the spindle fibers �M Goal: divide chromosomes equally between two daughter cells �M checkpoint goal: make sure sister chromatids are attached correctly to the spindle fibers before anaphase irreversibly separates them

Cell Cycle Checkpoints

Cell Cycle Checkpoints • Normal cells stop dividing in certain situations: ▫ Cells are in close contact ▫ Growth Factors stop sending signal ▫ Cell cycle checkpoint signals to stop dividing ▫ Apoptosis: programmed cell death

Cell Cycle and Cancer • Cancer develops when a single cell stops heeding the checkpoints – division continues indefinitely • Carcinogen: substances known to produce or promote the development of cancer

Cell Cycle and Cancer • Cancer ▫ Benign tumor: mass of abnormal cells that remain at the original site ▫ Malignant tumor: mass of abnormal cells invade and impairs the functions of one or more organs

Cell Cycle and Cancer