Morgan’s crossing-over hypothesis

Each homolog initially contains identical sister chromatids. A single crossover produces two recombinant chromatids. Completion of meiosis produces two parental gametes and two recombinant gametesEach homolog initially contains identical sister chromatids. A single crossover produces two recombinant chromatids. Completion of meiosis produces two parental gametes and two recombinant gametes

———-> ————-> ———> v . "'7+ mt m m mt m+ m m m+ IT?+ m m m* m m‘ m l l J W+ W+ W W W+ W+ W W W+ W W+ W W+ W W l W+ Homologous chromosomes Synaptonemal complex Crossover completed Gamete formation (end of (beginning of prophase l) formation (early prophase I) (end of metaphase I) telophase ll, four gametes) Crossing over creates _ arental and nonparental i p i gametes after segregation.