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BIOLOGY – MEIOSIS TO MENDEL - Homologous chromosomes: one set of chromosomes from each parent. - Sister Chromatids: attached at a centromere - Homologous chromosomes have the same band pattern when stained - Karyotype: chromosomes arranged from longest to shortest - Meiosis 1 -> chromosomes reduced by half - Meiosis 2 -> number of chromosomes does not change - 2 replicated -> 2 cells, each with 2 UNreplicated chromosome - Number of DNA drops twice, number of chromosomes drops once. - No S-Phase in meiosis 2 - Meiosis only occurs in specialized meiotic areas of the body - Meiosis generates genetic diversity o Crossing over between maternal and paternal homologous during prophase o Independent assortment/alignment of mat/pat homologous from different tetrads during metaphase o Random alignment of recombinant chromatids at metaphase 2
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Unformatted text preview: o Random fertilization of gamete -Prophase of meiosis -> chromosomes find their partners and pair.-Chromatids pair by sandwiching together-CROSSING OVER OCCURS AT PROPHASE-Independent assortment: Metaphase-Since sister chromatids are no longer identical, there are two possible orientations for each on the M2 plate. -Mendel o 150 years ago o Carefully controlled pollinations and guantitative analysis of several generations of pea plants o Looked at traits such as tall/short, inflated/constricted, purple/white flowers, etc-Variation in traits due to alleles -Organisms inherit 2 alleles for each trait-Dominant alleles determine appearance of zygotes-Two different homozygotes PPxpp -> F1 heterozygotes Pp-Two F1 -> F2 PP, Pp, Pp, pp 1:2:1 genotypes, 3:1 phenotype-...
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This note was uploaded on 10/23/2008 for the course BIO 1222 taught by Professor Maxwell during the Spring '08 term at UWO.

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