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Meiosis

Meiosis. Meiosis – germ cell go through 2 nuclear divisions that results in 4 daughter cells with half the number of chromosomes as the parent cell. Explains how gametes are produced daughter cells are not genetically alike.  may have different combination of genes.

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Meiosis

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  1. Meiosis • Meiosis – germ cell go through 2 nuclear divisions that results in 4 daughter cells with half the number of chromosomes as the parent cell. • Explains how gametes are produced • daughter cells are not genetically alike.  • may have different combination of genes

  2. Sexually reproducing organisms are capable of combining chromosomes from 2 parents to produce offspring. • The chromosomes that combine during sexual reproduction are contained in reproductive cells called gametes.

  3. Control of the Cell Cycle • http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__control_of_the_cell_cycle.html • Activity:  25 point extra creditGo to the onion root tip activity and complete the percentages activity.  • http://www.biology.arizona.edu/Cell_bio/activities/cell_cycle/cell_cycle.html •  Mitosis Rap • http://www.nclark.net/MitosisRap.mp3 • Mitosis Animation and Tutorialhttp://www.biology.arizona.edu/Cell_bio/tutorials/cell_cycle/cells3.html • http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.htmlhttp://www.sumanasinc.com/webcontent/animations/content/mitosis.html • Meiosis • http://www.youtube.com/watch?v=D1_-mQS_FZ0http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter19/animation__how_meiosis_works.html • http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter12/animations.html#    • Mitosis vs Meiosishttp://www.johnkyrk.com/meiosis.htmlhttp://www.pbs.org/wgbh/nova/baby/divide.html# http://www.pbs.org/wgbh/nova/baby/divi_flash.html • http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__comparison_of_meiosis_and_mitosis__quiz_1_.html

  4. Meiosis • like mitosis, meiosis follows Interphase and ends with cytokenisis

  5. The 1st meiotic division results in two cells with ½ the number of chromosomes as the parent cell. • The 2nd meiotic division is like mitosis; the number of chromosomes does not get reduced. Results in 4 daughter cells with half the # of chromosomes as the parent cell

  6. Prophase I • each chromosomes consist of two sister chromatids connected at the centromere • Homologous pairs of chromosomes come together, this event is called synapsis • Each pair of homologous chromosomes is called a tetrad. (4 chromatids that make up a homologous pair)

  7. Crossing over – exchange of genes between non- sister chromatids of a homologous pair • results in genetic recombination by producing a new mixture of genetic material.

  8. Metaphase I • Homologous pairs (tetrads) align in the middle of the cell.

  9. Anaphase I • homologous pairs separate and move to opposite ends of the cell. • Each chromosome consist of 2 chromatids

  10. Telophase I • Spindle fibers break down • 2 new nuclei form • One around each set of chromosomes • ½ the number of chromosomes as the original (parent) cells • End of Meiosis I

  11. Meiosis II

  12. Prophase II • Spindle fibers form

  13. Metaphase II • chromosomes line up at the equator

  14. Anaphase II • sister chromatids separate at the centromere and move to opposite poles ttp://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter19/animation__how_meiosis_works.html

  15. Telophase II • 4 new nuclei appear; one around each set of chromosomes • followed by cytokenesis

  16. end up with 4 cells that are all haploid with only 1 chromatid for each chromosome

  17. Review • http://www.biology.arizona.edu/cell_bio/tutorials/meiosis/problems.html

  18. Meiosis - Males

  19. Meiosis in Females

  20. Meiosis II • prophase II: spindle fibers attach to the duplicated chromosomes and begin moving them to the spindle equator. • metaphase II: chromosomes align at the cell equator with one chromatid facing one pole and the other chromatid facing the opposite pole. • anaphase II: the chromatids separate and are now called chromosomes. The chromosomes migrate toward the two poles. • telophase II: the chromosomes arrive at the opposite poles, and the cytoplasm divides. The two meiotic divisions result in four haploid cells.

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