The homologous pairs move toward the metaphase plate

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The homologous pairs move toward the metaphase plate (Campbell p.244) (Riley) Metaphase I Pairs of homologous chromosomes are arranged on the metaphase plate Both chromatids of a homologue are attached to kinetochore microtubules from one pole Anaphase I Chromosomes move toward the poles Sister chromatids remain attached at the centromere and move toward the same pole Homologous chromosomes move toward opposite poles Telophase I and Cytokinesis Cytokinesis forms 2 haploid duaghter cells In animal cells a cleavage furrow is formed In some cells the nuclear envelope and nucleoli re-form No chromosome replication occurs Prophase II A spindle apparatus forms Chromosomes composed of 2 chromatids move toward the metaphase II plate
Metaphase II Chromosomes are positioned on the metaphase plate The kinetochores of sister chromatids are attached to microtubules extending from opposite poles Anaphase II Centrosomes of each chromosome finally separate and the sister chromatids come apart Sister chromatids move individually towards opposite poles Telophase II and Cytokinesis Nuclei form Meiotic division of 1 parent cell produces 4 daughter cells Each of the 4 daughter cells is genetically distinct from the others and from the parent cell (Campbell p.245) (Riley) Crossing Over In the early part of prophase I, two nonsister chromatids, one from mom and one from dad, break at the same place in their DNA and then rejoin the other chromatid where it was broken off. Normally, a human chromosome can expect to go through crossing over 1-3 times depending on its size and position of the centromere. Crossing over allows us to get a mix of both parents genes and thus leads to genetic variation (campbell 248). (Ramey) Video: (Kaufman)
(Brandenburg) Summary of the Stages of Meiosis
Meiosis, unlike mitosis, has 2 consecutive cell divisions called meiosis I and meiosis II. These divisions result in 4 daughter cells that each have half as many chromosomes as the parent cell. Mitosis only produce 2 daughter cells. In meiosis, a single homologous pair of chromosomes in a diploid cell is replicated and copied into 4 daugher haploid cells. After the chromosomes replicate during interphase, the homologous chromosomes separate during meiosis I. Then during meiosis II, the sister chromatids separate, producing 4 daughter cells. The diploid cell must divide twice during meiosis in order to produce the haploid daughter cells. (Campbell p.243) (Riley)
Life Cycles Alternation of generations Organisms with multicellular haploid and diploid stages  Inheritance  Reproduction: What is the outcome of asexual?

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