Cell Cycle and Mitosis Organization of the process of cell division! “Omnis cellula e cellula” Rudolf Virchow 1855 Types of Cell Division • Binary Fission – Prokaryotic Cell Division • Mitosis – Eukaryotic Cell Division • Meiosis – Production of sex cells Do all cells divide? • Cells that divide – – – – Stem Cells Glial cells in the brain Skin cells Cancer cells • Cells that don’t really divide (senescence) – Red Blood Cells – Neurons – Heart Cells Why might a cell need to divide? • • • • • Embryonic Development Repair Tissues Cells have a max surface area to volume ratio Asexual reproduction Cancer Cell Cycle in Eukaryotes What is the meaning of mitosis? • Interphase • Mitosis • Cytokinesis How is the genetic material organized How does the cell change during the cell cycle? • Are the stages discreet or continuous? • What is important about metaphase? How are changes in genetic material detected? • Changes in nuclear material first detected by dark stain of the nuclear material = “Chromo” • Advances in light microscopy show role of centrosomes, spindle fibers, kinetochores Phases of mitosis • See pg 232 • Note activity of chromosomes, envelope, spindle during each stage • Chromosome “walking” • Review: Biovisions video What tells a cell to divide? • External Controls – Growth Factors • Internal Controls – Cyclins – CDK What proteins control cell growth internally? • CDK: always present in cells • Cyclin: level varies throughout the cell cycle • MPF: “mitosis promoting factor” --occurs when cyclin binds to CDK. How does cyclin’s structure allow for its function of promoting mitosis? Cancer • Cancer is when the cell cycle goes wrong. • What might happen to cause a cell cycle to wreak havoc?