Meiosis Diploid to Haploid Crossing Over Synapsis Homologous

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,

Crossing Over During Meiosis • Happens during prophase I • Physical switching of chromosome

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Meiosis

Diploid to Haploid

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

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

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

Crossing Over During Meiosis • Happens during prophase I • Physical switching of chromosome • Genes get switched causing unexpected outcomes • Adds to genetic variation!