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Cell Cycle/Cell Division Mitosis and cytokinesis Mitosis •Growth – Somatic (body) cells undergo mitosis for growth. •Maintenance – Somatic cells use mitosis to repair damage. •Asexual Reproduction – Mitosis is the process used by some organisms to reproduce (budding,etc…) Steps to Mitosis • Interphase • Steps to Mitosis – – – – – Prophase Metaphase Anaphase Telophase Cytokinesis Interphase • 1- DNA replication • 2- transcription and translation (normal cell growth) Prophase • Chromatins condense • Nuclear envelope dissolves freeing DNA in the cell. Animal cells only: • Centrioles form spindle fibers Metaphase • Metaphase Plate (chromosomes line up in the middle of the cell) • Highly organized so that both new cells will get exactly the same DNA • Spindle fibers completely attached to centromeres Anaphase • Paired chromosomes are pulled to opposite sides • Each chromosome is an exact copy of one original chromosome. • Each end is considered a polar end. Telophase • Chromatids end up at separate poles, spindle fibers begin to dissolve • Nuclear envelopes begins to form • Cell starts to pinch off through cytokinesis Cytokinesis • Division of all the rest of cellular organelles into two identical daughter cells. Animal Cells: Actin forms around the center of the cell and contract pinching off two cells. Plants Cells: New cell plate created between the two cells. Mitosis Animation • http://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/cells3.html