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Cellular Reproduction Cell Division cellular material is divided between new daughter cells Nuclear division: Mitosis or Meiosis Cytoplasmic division: Cytokinesis Mitosis and Meiosis in the Human Life Cycle Cell Cycle with Mitosis G2 assembly of components for division S chromosomes replicate Mitosis P M A T Mitosis P = prophase M = metaphase A = anaphase T = telophase cytokinesis G1 cytoplasm doubles Interphase Interphase G1 = growth phase 1 S = synthesis phase G2 = growth phase 2 Applying Your Knowledge 1. 2. 3. 4. 5. G1 S G2 Mitosis Cytokinesis A. When does nuclear division occur? B. When are the chromosomes duplicated? C. When do the cytoplasmic contents double? Interphase nucleus nucleolus Chromatin is diffuse, individual chromosomes cannot be distinguished. Prophase Chromosomes condense. Spindle forms. Nucleolus disappears. Nuclear envelope breaks down. centromere chromatid chromatid Sister Chromatids are held together at their centromeres. Each chromosome appears as a pair of chromatids attached at the centromere. Metaphase Chromatid pairs align at the cell equator. Anaphase Sister chromatids separate and are drawn to opposite poles by spindle fibers. Telophase Chromosomes have reached poles of cell. Spindle disperses. Nuclear envelope surrounds chromosomes. Chromosomes become diffuse, nucleolus reforms. Telophase + Cytokinesis These phases can overlap in time. New Daughter Cells Cytokinesis in animal cells Cytokinesis in plant cells Applying Your Knowledge 1. 2. 3. 4. Prophase Metaphase Anaphase Telophase A. When do chromosomes line up at the cell equator? B. When are sister chromatids first visible? C. When do sister chromatids separate from each other? Comparing Mitosis and Meiosis Mitosis Cell type at start Cell type at end Are products identical? (Y/N) Number of cells produced Number of chromosome duplications Pairing of homologues (Y/N) Crossing-over (Y/N) Number of chromosome divisions Meiosis Comparing Mitosis and Meiosis Cell type at start Cell type at end Are products identical? (Y/N) Number of cells produced Number of chromosome duplications prior to Pairing of homologues (Y/N) Crossing-over (Y/N) Number of chromosome divisions Mitosis Meiosis Diploid Diploid Yes Two One Diploid Haploid No Four One No No One Yes Yes Two