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Slides cover Meiosis and Mendelian/ Nonmendelian outlines . Interphase. MITOSIS. MEIOSIS. Chiasma (site of crossing over). Parent cell (before chromosome replication). MEIOSIS I. Propase. Prophase I. Chromosome replication. Chromosome replication. Tetrad formed by
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MITOSIS MEIOSIS Chiasma (site of crossing over) Parent cell (before chromosome replication) MEIOSIS I Propase Prophase I Chromosome replication Chromosome replication Tetrad formed by synapsis of homologous chromosomes Duplicated chromosome (two sister chromatids) 2n = 6 . Chromosomes positioned at the metaphase plate Tetrads positioned at the metaphase plate Metaphase I Metaphase Anaphase Sister chromatids separate during anaphase Anaphase I Homologues separate during anaphase I; sister chromatids remain together Telophase Telophase I Haploid n = 3 Daughter cells of meiosis I 2n 2n MEIOSIS II Daughter cells of mitosis n n n n Daughter cells of meiosis II Sister chromatids separate during anaphase II
Epididymis Seminiferous tubule Testis Cross section of seminiferous tubule Spermatogenesis Spermatogonium Sertoli cell nucleus Mitotic division, producing large numbers of spermatogonia Differentiation and onset of meiosis I Primary spermatocyte (in prophase of meiosis I) Meiosis I completed Secondary spermatocyte Meiosis II Lumen of Seminiferous tubule Early spermatids Spermatids (at two stages of differentiation) Differentiation Neck Sperm cells Tail Midpiece Head Plasma membrane Acrosome Nucleus Mitochondria
Ovary Primary germ cell in embryo Differentiation Oogonium in ovary Oogonium Mitotic division Primary oocyte within follicle Oogenesis in the ovaries Primary oocyte Completion of meiosis I and onset of meiosis II Growing follicle Secondary oocyte First polar body Ovulation Mature follicle Entry of sperm triggers completion of meiosis II Ruptured follicle Second polar body Ovum Ovulated secondary oocyte Corpus luteum Degen- erating corpus luteum
MITOSIS MEIOSIS Chiasma (site of crossing over) Parent cell (before chromosome replication) MEIOSIS I Propase Prophase I Chromosome replication Chromosome replication Tetrad formed by synapsis of homologous chromosomes Duplicated chromosome (two sister chromatids) 2n = 6 Chromosomes positioned at the metaphase plate Tetrads positioned at the metaphase plate Metaphase I Metaphase Anaphase Sister chromatids separate during anaphase Anaphase I Homologues separate during anaphase I; sister chromatids remain together Telophase Telophase I Haploid n = 3 Daughter cells of meiosis I 2n 2n MEIOSIS II Daughter cells of mitosis n n n n Daughter cells of meiosis II Sister chromatids separate during anaphase II
Key Maternal set of chromosomes Possibility 2 Possibility 1 Paternal set of chromosomes Independent Assortment Two equally probable arrangements of chromosomes at metaphase I Metaphase II Daughter cells Combination 3 Combination 2 Combination 4 Combination 1
Dominant phenotype, unknown genotype: PP or Pp? Recessive phenotype, known genotype: pp Test Cross If Pp, then 1 2 offspring purple and 1 2 offspring white: If PP, then all offspring purple: p p p p P P Pp Pp Pp Pp P P pp pp Pp Pp
Key Maternal set of chromosomes Possibility 2 Possibility 1 Paternal set of chromosomes Independent Assortment Two equally probable arrangements of chromosomes at metaphase I Metaphase II Daughter cells Combination 3 Combination 2 Combination 4 Combination 1
BbCc BbCc Sperm bC Bc 1 1 1 1 BC bc 4 4 4 4 Epistasis 1 BC BBCC BbCC BBCc BbCc 4 1 bC BbCC bbCC BbCc bbCc 4 BBcc Bbcc BBCc BbCc 1 Bc 4 bbcc Bbcc 1 bbCc bc BbCc 4 9 3 4 16 16 16
AaBbCc AaBbCc aabbcc Aabbcc AaBbcc AaBbCc AABbCc AABBCc AABBCC Polygenic Inheritance&Norm of the Reaction 20/64 15/64 Fraction of progeny 6/64 1/64
First generation (grandparents) Ww ww ww Ww Second generation (parents plus aunts and uncles) . Ww ww ww Ww Ww ww Third generation (two sisters) WW ww or Ww Widow’s peak No widow’s peak Dominant trait (widow’s peak)
First generation (grandparents) Ff Ff ff Ff Second generation (parents plus aunts and uncles) FF or Ff ff ff Ff Ff ff . Third generation (two sisters) ff FF or Ff Free earlobe Attached earlobe Recessive trait (attached earlobe)
Female (XX) Karyotype(Remember… “kary” means “nucleus”)
Recombination frequencies Linkage Map based on Crossover frequency 9% 9.5% 17% vg b cn Chromosome