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Meiosis The Continuation of Life. Meiosis: The Continuation of Life.

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Meiosis Meiosis The Continuation of Life The Continuation of Life
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  • MeiosisThe Continuation of Life

  • Meiosis: The Continuation of Life

  • Homologous ChromosomesPaired chromosomes

    One from each parent

    Genes for same traitAllelesSame order on chromosome

  • Homologous Chromosomes

  • Diploid vs. HaploidDiploid Cell that has TWO of each kind of chromosome (parent)2n

    Haploid Cell that has ONE of each kind of chromosome1n

  • QuestionWhat would happen if Mitosis was the only way our cells could divide?

    23pairs 46pairs 96pairsetc.

    We need a way to divide the Chromosome # in half! What is this called??Meiosis!

  • MeiosisPurpose make haploid cells

    GametesEggSperm

    Form Zygote

  • Phases of MeiosisMeiosis I

    Prophase IMetaphase IAnaphase ITelophase I

    Meiosis II

    Prophase IIMetaphase IIAnaphase IITelophase IICytokinesis

  • Prophase ISame as in MitosisBut

    Homologous Chromosomes find each other

    Synapsis Tetrads

  • Prophase ISynapsis

    Crossing over occurs

    Exchange of Genetic material

  • Crossing OverCrossing Over and its products!

  • Metaphase IHomologous pairs line up

    Tetrads still together

  • Anaphase IHomologous Chromosomes separate

    Independent Assortment

  • Telophase IJust like Telophase in MitosisChromosomes unwindNuclear membrane forms

  • Meiosis IIJust like Mitosis!!

    Meiosis IIProphase IIMetaphase IIAnaphase IITelophase II

  • Prophase IIChromosomes appearCentrioles migrateSpindle fibers

  • Metaphase IIChromosomes line upLike mitosis

  • Anaphase IIChromosomes separate like in mitosisMove to ends of cell

  • Telophase IINuclear membrane formsChromatids unwind Chromatin

    FinallyCytokinesis!

  • ProductsFrom single diploid (2N) 4 Haploid (1N)

  • Cellsalive!Meiosis: An Interactive Animation

    Web Lesson Meiosis

  • Mitosis vs. Meiosis

  • GametesWhy are some of the chromosomes different colors?

    Crossing Over!

  • VariationGenetic Variation is provided by meiosis

    Because of assortment 70 trillion possibilities

    Crossing Over increases that numberReason for great variety of people

  • Mistakes in MeiosisNondisjunction the failure of homologous chromosomes to separate properly

    Trisomy 1 extra chromosomeMonosomy 1 less chromosomePolyploidy extra set of all chromosomes

  • TrisomyTrisomy 21Downs Syndrome

    Flattened face

    Shorter than normal

    Heart defects

  • MonosomyUsually lethal but, but not in

    Turners Syndrome

    Look at KaryotypeWhat is wrong here?

  • Turners Syndrome

  • PolyploidyWhole extra set of chromosomes(3n) or (4n)

    Death animal zygotes

    Often occurs in plantsBigger and Healthier

  • Phase? #1

  • QuestionWhat separates during Meiosis I?

    Homologous Chromosomes

  • QuestionWhat type of cell results from meiosis I?

    Haploid!

  • QuestionWhat separates during Meiosis II?

    Sister Chromatids

  • Questions?

    *


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