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Mitosis to Meiosis

Mitosis to Meiosis. Sept. 8, 2005. Meiosis: Two Divisions. How does Meiosis I differ from Mitosis? What kinds of regulatory systems would achieve the conversion of Mitosis into Meiosis I?. 2c. 1c. 2c. Mitosis – G 1 and G 2 Chromosomes. Pairing of Homologs. Synaptonemal Complex

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Mitosis to Meiosis

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  1. Mitosis to Meiosis Sept. 8, 2005

  2. Meiosis: Two Divisions • How does Meiosis I differ from Mitosis? • What kinds of regulatory systems would achieve the conversion of Mitosis into Meiosis I?

  3. 2c 1c 2c Mitosis – G1 and G2 Chromosomes

  4. Pairing of Homologs Synaptonemal Complex (protein) with “recombination granules” Leptotene Zygotene Chromosome Axis (protein) with scaffolds and loops of chromatin Meiosis – Zygotene Pairs of Homologs

  5. Kinetochore(chromatid structures) Secondary constriction (site of rDNA), ribosomal genes

  6. Cell Cycle Controls • Cyclins (accelerators) • Kinases (breaks) • Hormones (initiators, inhibitors) • DNA replication process • DNA repair processes (p53 protein) • Microtubule (Spindle) processes • Forces to move chromosomes into homologus pairs (tetrads) • Forces to uncoil, snip DNA, splice DNA, etc.

  7. Exchanges that give new combinations from grandparents

  8. One or Two Exchanges? Linked LociShare a chromosome What is necessary to have an exchange between chromosomes?

  9. DNA repair Crossing Over Blue Loop displaces red DNA Blue and red are non-sister chromatids that can form a heteroduplex

  10. A a NCO A a A A co Geneconversion a a a A Gene Conversion is when A is converted to a, or vice versa. If a pairing happens where Base Pairs’ differ: NCO

  11. What new process “appear”? • Pairing • Enzymes to form pairing proteins • Transport enzymes (proteins) into nucleus • Location in right place, right amount and relationships • Chromatid breaking, rejoining • Enzymes to uncoil • Enzymes to break • Enzymes to join

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