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MEIOSIS

MEIOSIS. Prepared By: Miss Andrea Veira 20 th February, 2011. What is it?. Another form of cell division Occurs in two parts: meiosis I and meiosis II Allows haploid number (n) of chromosomes to form Allows variation Used in fertilisation/sexual reproduction.

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MEIOSIS

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  1. MEIOSIS Prepared By: Miss Andrea Veira 20th February, 2011

  2. What is it? • Another form of cell division • Occurs in two parts: meiosis I and meiosis II • Allows haploid number (n) of chromosomes to form • Allows variation • Used in fertilisation/sexual reproduction

  3. Meiosis Vs. Mitosis/Haploid Vs. Diploid http://bio.rutgers.edu/~gb101/lab10_meiosis/meiosis_web/review/meiosis_mitosis.jpg

  4. Cell Division To Allow Fertilisation http://www.carolguze.com/images/cell%20division/meiosis5.jpg

  5. Stages Of Meiosis http://www-bcf.usc.edu/~forsburg/images/meiosis2.jpg

  6. http://image.wistatutor.com/content/feed/tvcs/meiosis-big.gifhttp://image.wistatutor.com/content/feed/tvcs/meiosis-big.gif http://image.wistatutor.com/content/feed/u2044/meiosis.jpg

  7. Meiosis Ensures: • Each daughter cell has a haploid (n) number to reform the diploid (2n) number after fertilisation. • Each daughter cell has different genes which gives variation.

  8. Some Definitions: Homologous Pairs Of Chromosomes-are similar chromosomes, one from the mother and one from the father. Chromatids- replicas of chromosome held in pairs by a centromere. So…What’s a centromere?

  9. Stages Of Meiosis • Genetic info randomly exchanged between chromatids (Prophase I) • Homologous Chromosomes align at equator randomly then separate and move to poles of cell • Cell becomes two • Division repeated;random line up at equator • Chromatids separate, 4 daughter cells form, each with a haploid number of chromosomes

  10. How Is Variation Achieved? • Crossing over is random • Lining up at equator (metaphase I) is random • Lining up at equator (metaphase II) (now chromatids) is random -What’s the common word here? -Why is crossing over important in meiosis?

  11. Comparing Mitosis And Meiosis

  12. Comparing Mitosis And Meiosis Taken From CXC Biology By Linda Atwaroo-Ali Edited By Dr. Mike Taylor 2003

  13. Links • http://www.brightstorm.com/science/biology/cell-division-and-reproduction/meiosis • http://videos.howstuffworks.com/science/meiosis-videos-playlist.htm

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