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10.2 Meiosis

10.2 Meiosis. Warm-Up. Cross TT X Tt Give the genotypic and phenotypic ratios. Sexual Reproduction. Male - spermatogenesis Occurs frequently Produce sperm cells Female - Oogenesis Occurs every 28 days Produce one egg Do not copy. Meiosis is Sex Cells dividing.

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10.2 Meiosis

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  1. 10.2 Meiosis

  2. Warm-Up • Cross TT X Tt • Give the genotypic and phenotypic ratios

  3. Sexual Reproduction • Male - spermatogenesis • Occurs frequently • Produce sperm cells • Female - Oogenesis • Occurs every 28 days • Produce one egg Do not copy

  4. Meiosis is Sex Cells dividing • One mother cell produces four daughter cells • Each daughter cell has haploid chromosome # (1/2 of what mother had) • Occurs in sex cells (sperm and egg)

  5. Meiosis Has 8 Stages • 1. Interphase - mature cell ready for cell division • 2. Prophase I - chromosomes are short, thick and double attached by centromere • 3. Metaphase I - tetrads align at equator • 4. Anaphase I - Tetrads split and move to opposite poles • 5. Telophase I - events occur in the reverse of prophase I • Don’t copy

  6. Meiosis Has 8 Stages • 6. Metaphase II - chromatids align at equator • 7. Anaphase II - chromatids split and move to opposite poles • 8. Telophase II - 4 cells with haploid #(new sperm and egg cells) • Don’t Copy

  7. http://www.cellsalive.com/meiosis.htm

  8. Mitosis / Meiosis Comparison • Mitosis • Asexual and sexual • Identical cells produced • Same #chromosomes (46) • Body cells • One Division • Two cells made • 20 minutes to one hour • Meiosis • Sexual cell division • Cells different • Different number of chromosomes (23) • Sex cells • Two divisions • 4 cells made • Occurs in days

  9. Genetic Variation • Crossing Over • Genetic Recombination

  10. Mistakes in Meiosis • Trisomy - extra chromosome (down syndrome) • Monosomy - lacking a chromosome (most lethal, Turner Syndrome) • Triploidy - three sets of chromosomes • Polyploidy - more than the usual number of chromosomes (rare in animals, common in plants)

  11. Meiosis Vocab • Gene - portion of DNA that is genetically active, controls traits • Chromosome - Thread like, humans 23 pairs • Haploid chromosome # (n) - single set of chromosomes • Diploid chromosome # (2n) - two of each kind in a cell

  12. Meiosis Vocab • Homologous Chromosome - same • Allele - one-half of a gene pair (T or t) • Gamete - Sex cell, reproductive cell • Sperm - male haploid # (Father) 23 chromosomes • Egg - female haploid # (Mother) 23 chromosomes • Zygote - fertilized egg by a sperm, diploid number (2n) = 46 chromosomes, 23 pairs

  13. Karyotypes • Organized photo of a person’s chromosome • Autosomes vs. sex chromosomes

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