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Chapter 11-4: Meiosis

Chapter 11-4: Meiosis. Production of Sex Cells. Introduction. Mitosis and Meiosis are somewhat similar, but have 2 completely different goals.

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Chapter 11-4: Meiosis

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  1. Chapter 11-4: Meiosis Production of Sex Cells

  2. Introduction • Mitosis and Meiosis are somewhat similar, but have 2 completely different goals. • Mitosis used in growth, healing, and reproduction in unicellular organisms. Whereas, Meiosis is SOLELY used for the production of gametes (sex) cells in multicellular organisms.

  3. Mitosis VS. Meiosis M Process: 1 round of division Process: 2 rounds of division End result: 4 genetically different daughter cells End Result: 2 identical daughter cells

  4. Humans have two full sets of chromosomes • (one set from our male parent and one from our female parent.)

  5. Each pair of chromosomes are known as “homologous” because they share the same genes, but likely very different alleles.

  6. Ploidy: How many sets of chromosomes an organism has. • Because we (humans) have two complete sets of chromosomes, we are said to be diploid.

  7. Ploidy Homologous pair The diploid number is referred to as 2N. For humans, 2N = 46. Each human somatic or body cell contains 46 chromosomes. Human Karyotype

  8. Ploidy Each human gamete or sex cell only has a single set of chromosomes and are referred to as haploids. Human Karyotype

  9. For our sperm or eggs, the haploid number is 23. • ________ = _______ (sperm and eggs) • ________ = _______ (every other cell in our body) n 23 2n 46 http://www.angelbabygifts.com/ Image by Riedell Image by Riedell n n 2n EGG +  SPERM haploid haploid diploid http://www.acmecompany.com/stock_thumbnails/13217.forty-six_chromosomes.jpg

  10. The Process of Meiosis How are haploid (N) gamete cells produced from diploid (2N) cells? Meiosis is a process of reduction and division in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell.

  11. Watch carefully! Diploid number? 4 chromosomes Homologous pairs? 2 pairs http://www.tokyo-med.ac.jp/genet/anm/mimov.gi

  12. INTERPHASE By the end of G2, meiosis is ready to begin. Click! MEIOSIS I

  13. PROPHASE I METAPHASE I Click! MEIOSIS I Click! Click!

  14. ANAPHASE I TELOPHASE I Click! Click! MEIOSIS I

  15. PROPHASE II METAPHASE II Click! Click! MEIOSIS II

  16. ANAPHASE II TELOPHASE II Click! Click! MEIOSIS II

  17. 11.4 Meiosis Notice how meiosis differs between males and females. Spermatogenesis: Creates 4 genetically different sperm

  18. Notice how meiosis differs between males and females. Oogenesis: Creates 1 viable egg and 3 polar bodies that are digested by lysosomes.

  19. 11.4 Meiosis Mitosis resulted in the production of two genetically identical diploid cells, whereas meiosis produces four genetically different haploid cells.

  20. 11.4 Meiosis Summary of MITOSIS: (Genetically Identical) Mitosis allows an organism's body to grow and replace cells. In asexual reproduction, a new organism is produced by mitosis of the cell or cells of the parent organism.

  21. 11.4 Meiosis Summary of MEIOSIS: (Genetically Different) A diploid cell but produces four haploid (N) cells. These cells are genetically different from the diploid cell and from one another. Meiosis is how sexually reproducing organisms produce gametes.

  22. LET SLEEPING DOGS LIE

  23. http://www.angelbabygifts.com/ Image by Riedell Image by Riedell n _ __ EGG +  SPERM diploid haploid ________

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