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Process of meiosis

Process of meiosis. CSCOPE Unit 08 Lesson 02. Asexual vs. sexual reproduction. Asexual vs. sexual reproduction. What is the advantage of an organism that reproduces sexually rather than asexually?

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Process of meiosis

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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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