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Cellular Reproduction

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. 2n = diploid = 2 sets of chromosomes

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Cellular Reproduction

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  1. Cellular Reproduction Cell Division cellular material is divided between new daughter cells Nuclear division: Mitosis or Meiosis Cytoplasmic division: Cytokinesis

  2. Mitosis and Meiosis in the Human Life Cycle 2n = diploid = 2 sets of chromosomes n = haploid = 1 set of chromosomes

  3. Cell Cycle with Mitosis Mitosis P M Mitosis P = prophase M = metaphase A = anaphase T = telophase A G2 T assembly of components for division cytokinesis Interphase G1 = growth phase 1 S = synthesis phase G2 = growth phase 2 S G1 cytoplasm doubles chromosomes replicate Interphase

  4. When does nuclear division occur? When are the chromosomes duplicated? When do the cytoplasmic contents double? G1 S G2 Mitosis Cytokinesis Applying Your Knowledge

  5. Interphase nucleus nucleolus Chromatin is diffuse, individual chromosomes cannot be distinguished.

  6. Prophase Chromosomes condense. Spindle forms. Nucleolus disappears. Nuclear envelope breaks down.

  7. centromere chromatid chromatid Sister Chromatids are held together at their centromeres. Each chromosome appears as a pair of chromatids attached at the centromere.

  8. Metaphase Chromatid pairs align at the cell equator.

  9. Anaphase Sister chromatids separate and are drawn to opposite poles by spindle fibers.

  10. Telophase Chromosomes have reached poles of cell. Spindle disperses. Nuclear envelope surrounds chromosomes. Chromosomes become diffuse, nucleolus reforms.

  11. Telophase +Cytokinesis New Daughter Cells These phases can overlap in time.

  12. Cytokinesis in animal cells Cytokinesis in plant cells

  13. When do chromosomes line up at the cell equator? When are sister chromatids first visible? When do sister chromatids separate from each other? Prophase Metaphase Anaphase Telophase Applying Your Knowledge

  14. Outcome of Meiotic Divisions Human Cell with 46 chromosomes (Diploid) Duplication of Cell Contents Two Chromosomal Divisions(Meiosis I and Meiosis II) 4 Genetically-Different Human Cells , Each with 23 chromosomes (Haploid)

  15. Homologous Chromosome Pairs • Diploid cells have pairs of chromosomes • Each homologous chromosome pair is genetically matched so that the genes are arranged in the same order

  16. Cell Cycle With Meiosis Meiosis Meiosis M1 = meiosis I M2 = meiosis II M1 G2 M2 assembly of components for division cytokinesis S Interphase G1 = growth phase 1 S = synthesis phase G2 = growth phase 2 G1 cytoplasm doubles chromosomes replicate Interphase

  17. When does chromosome duplication occur? When do the cytoplasmic contents double? When does chromosomal division occur? G1 phase S phase G2 phase Meiosis I and II Applying Your Knowledge

  18. Meiotic Divisions • Meiosis I: reduction division Separation of homologous chromosomes into two different nuclei Chromosome number reduced to haploid • Meiosis II: equational division Duplicated chromosomes separate No change in chromosome number

  19. Phases of Meiosis I

  20. Centromeres Chromatid(duplicate) Non-sister chromatids Chromosomes condense. Synapsis (pairing) of homologs occurs. Crossing-over occurs at chiasma (contact points).

  21. Crossing Over HomologousPairs Exchange Genetic Information Chromosomes with combinations of maternal and paternal traits

  22. I Homologues move to opposite poles of the cell. Chromosome pairs align at the center of the spindle.

  23. Cytokinesis along the central plane yields two haploid cells with duplicated chromosomes. Prior to the start of Meiosis II, there may be a pause called interkinesis but the chromosomes do not duplicate a second time. Homologues reach opposite poles.

  24. Phases of Meiosis II

  25. Sister chromatids separate at centromeresand move to opposite poles. Chromosomes align at the cell equators on the new spindles. Chromosomes condense.

  26. After cytokinesis, four genetically-different haploid cells are formed. Daughter chromosomes reach opposite poles.

  27. Sperm formation • Equal divisions of cytoplasm • Four functional products per meiosis • Egg formation • Unequal divisions of cytoplasm • Small polar bodies formed • One functional product per meiosis

  28. When do sister chromatids separate? When does crossing over occur? When do homologous pairs line up at the cell equator? Prophase I Metaphase I Anaphase I Metaphase II Anaphase II Applying Your Knowledge

  29. Comparing Mitosis and Meiosis

  30. Comparing Mitosis and Meiosis

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