Meiosis Diploid to Haploid Interphase Meiosis I prophase

Crossing Over • Synapsis- Homologous Pairs line up = Tetrad • During synapsis the

Law of Independent Assortment • During metaphase, as the homologous pairs line up the

Formation of Gametes • Meiosis only occurs in the reproductive cells…all other cells undergo

Karyotype • 46 chromosomes, 23 pair • One of each pair was from mom,

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Meiosis

Diploid to Haploid

Interphase

Meiosis I prophase 1

Crossing Over • Synapsis- Homologous Pairs line up = Tetrad • During synapsis the chromstids within a homologous pair may twist around each other and break off and attach to the other homologous pair = Crossing Over • Results in exchange of genetic material between maternal and paternal chromosomes = genetic recombination

Meiosis I metaphase 1 and anaphase 1

Law of Independent Assortment • During metaphase, as the homologous pairs line up the orientation of maternal and paternal chromosomes is random – Not all maternal go to one side, and paternal the other…. it is mixed • Law of independent assortment • As the homologous pairs are separated in anaphase, they maternal and paternal chromosomes have random separation – Results in genetic variation

Law of Independent Assortment

Meiosis I telophase 1

Meiosis II prohase 2

Meiosis II metaphase 2 and anaphase 2

Meiosis II telophase 2

Formation of Gametes • Meiosis only occurs in the reproductive cells…all other cells undergo mitosis • Ending products of meiosis are haploid gametes – Eggs in female - oogenesis – Sperm in male - spermatogenesis • Fusion of sperm and egg results in a diploid cell

DNA v. Gene

Karyotype • 46 chromosomes, 23 pair • One of each pair was from mom, one from dad