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To be successful today …

To be successful today …. Pick up graded Notebooks Pull out why meiosis notes. BYOD Color of the day is Phones are in put away in backpacks. After warm up: Add to TOC & Glue in pages. NOTES: Why Meiosis? NOTES: Stages of Meiosis NOTES: Stages of Meiosis.

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To be successful today …

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  1. To be successful today… Pick up graded Notebooks Pull out why meiosis notes BYOD Color of the day is Phones are in put away in backpacks

  2. After warm up: Add to TOC & Glue in pages • NOTES: Why Meiosis? • NOTES: Stages of Meiosis • NOTES: Stages of Meiosis

  3. MEIOSIS 46 chromosomes 46 chromosomes Essential Question: How does meiosis differ from mitosis and how does meiosis create cells that are genetically different from the parent cell?

  4. Two Types of Cells 1) Somatic (body) cellsEX: skin, brain, liver, etc 2) Sex cellsEx: Cells in reproductive organs (testes & ovaries) Meiosis occurs in sex cells

  5. Meiosis Interphase I Prophase I Metaphase I Anaphase I Telophase I Prophase II Metaphase II Anaphase II Telophase II

  6. Meiosis takes place in two series of steps & includes TWO Divisions No second Interphase Meiosis I I, P, M, A, T + Meiosis II P, M, A, T Which means…no DNA replication before meiosis II

  7. Stages of Meiosis

  8. Interphase I • DNA replicates creating homologous chromosomes

  9. 1) PROPHASE I • Homologous chromosomes pair up forming a tetrad (4 chromatids) Images modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

  10. 2. CROSSING OVER OCCURS • Homologous chromosomes exchange DNA • Creates genetic diversity http://sps.k12.ar.us/massengale/genetics%20tutorial.htm

  11. 2) Metaphase I • Tetrads line up in the middle

  12. 3) Anaphase I- Tetrads pull apart

  13. 4) Telophase I- Two new cells are formed

  14. Meiosis II No Interphase II which means chromosomes are NOT copied again.

  15. 5) Prophase II~ TWO cells begin meiosis II

  16. 6) Metaphase II:chromosomesline up in the middle

  17. 7) Anaphase II: chromosomes are pulled to opposite ends of the cell

  18. 8) Telophase II / Cytokinesis ~The two cells divide to form 4 genetically different cells (gametes)

  19. End Result of Meiosis • Sex cells begin meiosis diploid (2 copies of each chromosome) • At the end of meiosis, four new cells (gametes)are formed

  20. End Result of Meiosis • Gametes are haploid (half # chromosomes as parent cell) • Gametes will mature into sperm or eggs for sexual reproduction

  21. Meiosis Video

  22. What are the major differences between Mitosis and Meiosis?

  23. Mitosis vs Meiosis Diploid Parent Cell Crossing over occurs 2 cell divisions 2 identical, diploid somatic cells 4 genetically different, haploid gametes

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