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The Cell Cycle and Mitosis

The Cell Cycle and Mitosis

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The Cell Cycle and Mitosis

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  1. The Cell Cycle and Mitosis • Cell Division in Prokaryotes • Prokaryotes hav one circular chromosome • Binary Fission- the division of a prokaryotic cell into two offspring cells • DNA is copied, forming two identical chromosomes • Cell grows until it reaches approximately twice the cell’s original size

  2. Cell division in Eukaryotes • Cell Cycle –repeating set of events in life of cell • Interphase- time between cell divisions • G1 phase- cells grow to mature size • S phase- cell’s DNA is copied (synthesized) • G2 phase- Time during which cell prepare fro cell division • Cell Division: • Mitosis- the nucleus of cell divides • Cytokinesis- division of cell’s cytoplasm

  3. Cell division in Eukaryotes https://wps.prenhall.com/wps/media/objects/486/498658/CDA8_1/CDA8_1b/CDA8_1b.htm

  4. Stages of Mitosis • Prophase • DNA condenses into chromosomes • Centrosomes move to opposite poles • Mitotic spindle starts to form

  5. Metaphase • Chromosomes move to center of dividing cell • Anaphase • Chromatids of each chromosome separate and move toward opposite poles

  6. Telophase • Spindle fibers disassemble • Chromosomes return to a less tightly coiled chromatin state • Nuclear envelope forms around each set of chromosomes • Nucleolus forms in each of the newly forming cells

  7. Cytokinesis- division of cytoplasm • In Animal Cells • Cytokinesis begins with a pinching inward of the cell; cleavage furrow • Cleavage furrow pinches the one cell into two cells • In Plant Cells • Vesicles from Golgi apparatus join together at midline of dividing cell to form Cell Plate https://wps.prenhall.com/wps/media/objects/486/498658/CDA8_2/CDA8_2a/CDA8_2a.htm

  8. Control of Cell Division • Control occurs at 3 main checkpoints • Cell growth (G1) checkpoint- if cell is healthy and has grown to suitable size during G1 phase, proteins initiate DNA synthesis (S phase) • DNA synthesis (G2) checkpoint- DNA repair enzymes check the results of DNA replication. IF ok, then cell proceeds with mitosis • Mitosis checkpoint- if cell passes this checkpoint, proteins signal the cell to exit mitosis. • Cancer, the uncontrolled growth of cells is caused by mutations in the checkpoint proteins