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Meiosis: Genetic Diversity and Reproduction Processes

Learn about the process of meiosis, including its four phases - Prophase I, Metaphase I, Anaphase I, and Telophase I. Discover how genetic diversity is achieved through meiosis, with important concepts like crossing over and independent assortment explained.

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Meiosis: Genetic Diversity and Reproduction Processes

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  1. Process of meiosis CSCOPE Unit 08 Lesson 02

  2. Asexual vs. sexual reproduction

  3. Asexual vs. sexual reproduction • What is the advantage of an organism that reproduces sexually rather than asexually? • An organism that reproduces sexually will have more genetic diversity than one that reproduces asexually.

  4. Meiosis i • Four Phases: • Prophase I • Metaphase I • Anaphase I (and) • Telophase I • Genetic diversity results from meiosis I.

  5. Prophase I • Homologous (same) chromosomes pair (synapsis) • Homologous pairs called bivalents—two chromosome with four chromatids • Nuclear membrane dissolves • Chromosomes attach to spindle fibers and begin to move

  6. Metaphase I • Homologous chromosomes (bivalents) line up at the equator to form tetrads. • Random orientation results in diversity. • 50/50 chance of getting either parent’s homologue for each chromosome Tetrad

  7. Anaphase I • Homologous chromosomes separate. • Chromosomes with TWO chromatids move to opposite poles. • Daughter cells will have 23 chromosomes (haploid) but with two chromatids.

  8. Telophase I • Nuclear membrane begins to reform • Cell may quickly move to meoisis II

  9. Meiosis II • Similar to mitosis BUT no synthesis phase (no DNA replication) • Chromatids are NOT identical because of crossing over (recombination). • Separates chromatids and produces two daughter cells with 23 chromosomes that have one chromatid each

  10. Important Concepts!!! • Crossing Over: Exchange of genetic information between homologous chromosomes that results in recombinant chromosomes and genetic diversity

  11. Important Concepts!!! • Independent Assortment: Chromosomes randomly line up during metaphase I, and there are various ways that the homologous chromosomes may line up—again resulting in genetic diversity http://www.mhhe.com/biosci/ap/ap_prep/bioD6.html

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