This is due to the fact that once the homologous

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- This is due to the fact that once the homologous chromosomes pairs (the maternal pair and parental pair) separate, only n chromosomes are found in each daughter cell (23 in humans) even though there are 46 chromatids present - Note there also may be a short rest period called interkinesis , during which the chromosomes will partially uncoil
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- The Cell Cycle: Stages of Meiosis II: - Characteristics: - This is similar to mitosis in that the sister chromatids (connected by a centromere), rather than the HC pairs, are being separated from each other - Prophase II: - In prophase II, the nuclear envelope dissolves, nucleoli disappears, the centrioles migrate to opposite poles, and the spindle apparatus begins to form - Metaphase II: - In metaphase II, the chromosome lines up in the middle on the metaphase plate (also known as the equatorial plate) - Anaphase II: - In anaphase II, the centromeres divide, separating the chromosome into its two sister chromatids. The sister chromatids are then pulled to opposite poles by SF - Telophase II: - In telophase II, a nuclear membrane forms around each new nucleus and cytokinesis follows forming two daughter cells Meiosis Cell Cycle:
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** Refer to picture in book if confused with this subject again** - Critical Thinking Question: - How does Meiosis contribute to Genetic Diversity? - 1) Crossing Over: During prophase of meiosis I, the double- chromatid homologous pairs of chromosomes cross over with each other and often exchange chromosome segments. This recombination creates genetic diversity by allowing genes from each parent to intermix, resulting in chromosomes with a different genetic complement. The exchange occurs between non-sister chromatids. Because genes often interact with each other, the new combination of genes on a chromosome can lead to new traits in offspring. - 2) Reduction to Haploid: Because the duplicated chromatids remain joined during meiosis I, each daughter cell receives only one chromosome of each homologous pair. This reduces the diploid number to haploid, and the distribution of each chromosome is random. This means that it is equally likely for a given chromosome to be distributed to either of the two daughter cells. By shuffling the
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genetic deck in this way, the gametes resulting from meiosis II have new combinations of maternal and paternal chromosomes, increasing genetic diversity. - 3) Random Chromatid Assortment: A third source of genetic diversity occurs during meiosis II, in which the sister chromatids separate and are randomly distributed to the daughter cells, the gametes. Crossing over in meiosis I leads to non-identical chromatids in meiosis II chromosomes. During anaphase of meiosis II, the centromere joining each chromatid pair dissolves, creating two chromosomes of each type. The outcome of which chromosome will go to which gamete is random, so that each gamete has a potentially unique combination of genetic material. A sizeable 2.3: The Reproductive System: - The Reproductive System: Introduction: - Biological sex is determined by the 23rd pair of chromosomes, with XX being female and XY being male .
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