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MEIOSIS The production of eggs and sperm The “Reduction Division ”

Meiosis is used in sexual reproduction to make genetically diverse gametes  genetically diverse individuals. MEIOSIS The production of eggs and sperm The “Reduction Division ” Mother Cell (2n) Gamete (1n). Starts with 46 Ends with 23.

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MEIOSIS The production of eggs and sperm The “Reduction Division ”

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  1. Meiosis is used in sexual reproduction to make genetically diverse gametes  genetically diverse individuals

  2. MEIOSIS The production of eggs and sperm The “Reduction Division ” Mother Cell (2n) Gamete (1n) Starts with 46 Ends with 23 Media Links\13_08Meiosis.mpg

  3. Pre- Germ Cell OR Pre-Reproductive Cell Mother Cell is diploid 2n = 46 BUT in this cartoon version ……… 2n= 4

  4. Interphase Pre-Reproductive Cell #8 M.C. is 2n #10 Nucleolus #2 duplication

  5. Prophase I #5 ds chromosomes #9 N.M. gone #12 Spindle Fibers #13 Synapsis & Tetrads #3 Crossing Over Media Links\13-07b-ProphaseI.mov

  6. Sister Chromatids Prophase I Non-Sister Chromatids

  7. Synapsis - Homologous Pairs of chromosomes come together Tetrad – 4 homologous chromatids Media Links\13-10-CrossingOver.mov

  8. Metaphase I #6 Homologous pairs of chromosomes align on equator Media Links\13-07c-MetaphaseI.mov

  9. Anaphase I #7 Homologous pairs of chromosomes separate and are pulled to poles #11 ½ of homologous pair is at 1 pole, the other ½ is at the other pole Media Links\13-07d-AnaphaseI.mov

  10. Telophase I Media Links\13-07e-TelophaseICytokin.mov Cytokinesis occurs #1 2 temporary daughter cells are 1n (ds)

  11. Meiosis I Summary • 1. Crossing Over Occurred • (Ensures Genetic Variation) • 2.Separated the • Homologous Pair of Chromosomes • Cell went from 2N to 1N (ds) • 3. Started as 2N = 46 (ds), ended as • N = 23 (ds)

  12. Interkinesis – Meiosis Intermission #1 Both cells are 1n (ds) #6 Intermission of Meiosis #8 Each daughter cell is genetically different Are these cells 1N or 2N?

  13. Prophase II #1 1n (ds) #5 ds chromosomes move to equator #8 each daughter cell is genetically different

  14. Metaphase II #1 1n (ds) #8 each daughter cell is genetically different #9chromosomes (ds) align on equator

  15. Anaphase II #2 Centromeres break #7 (ss) chromosomes are pulled to poles #4 (future) Daughter cells will be are1n (ss) #8 each daughter cell is genetically different

  16. Telophase II #3 Cytokinesis occurs #4 Daughter cells are 1n (ss) #8 Each daughter cell is genetically different Media Links\13-07f-MeiosisIICytokin.mov

  17. Gametes #4 #8 #4 Daughter cells are 1n (ss) #8 Each daughter cell is genetically different

  18. Meiosis II Summary • Separated the chromatids, • Centromeres broke • 2. 2 temporary daughter cells went from • Haploid (ds) to Haploid (ss) • 3. Started as n = 23 (ds) ended as • n = 23 (ss) Media Links\13_08Meiosis.mpg

  19. And Now It Is Time To Start The Meiosis Lab... Grab your Chromosomes Cups and begin!!!!!

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