what is the failure of a pair of homologous chromosomes to separate properly during meiosis?
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1: Nondisjunction in Meiosis: Nondisjunction occurs when homologous chromosomes or sister chromatids fail to separate during meiosis, resulting in an abnormal chromosome number. Nondisjunction may occur during meiosis I or meiosis II.
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During meiosis 1, the parent cell with double the normal amount of chromosomes, splits into two diploid cells (have enough chromosomes to survive). During meiosis 2, the two diploid cells each split into two haploid cells (have half the amount of chromosomes to survive). Meiosis ends with four haploid cells.
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1 Answer. During meiosis 1, the parent cell with double the normal amount of chromosomes, splits into two diploid cells (have enough chromosomes to survive). During meiosis 2, the two diploid cells each split into two haploid cells (have half the amount of chromosomes to survive). Meiosis ends with four haploid cells.
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Synapsis (also called syndesis) is the pairing of two homologous chromosomes that occurs during meiosis.
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Metaphase leads to anaphase, during which each chromosome's sister chromatids separate and move to opposite poles of the cell. Enzymatic breakdown of cohesin — which linked the sister chromatids together during prophase — causes this separation to occur.
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The tetrad formation occurs during the first stage of meiosis that is prophase 1. In fact, the 2 homologous chromosomes align next to each other and as each chromosome consists of 2 sister chromatids, overall it looks like a group of 4. This is when the tetrad can be seen.
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Homologous and non-homologous chromosomes are the two types of chromosomes found in the genome. Homologous chromosomes pair during meiosis. The homologous pair consists of alleles of the same genes in the same loci in both chromosomes. But, non-homologous chromosomes consist of alleles of different genes.
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Homologous chromosomes are made up of chromosome pairs of approximately the same length, centromere position, and staining pattern, for genes with the same corresponding loci. One homologous chromosome is inherited from the organism's mother; the other is inherited from the organism's father.
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Homologous chromosomes containing the two chromatids come together to form tetrads, joining at their centromeres (2n 4c). This is when “crossing over” occurs, which creates genetic variation. Metaphase I: The tetrads line up along the metaphase plate.
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Homologous chromosomes are present in both mitosis and meiosis, but they don't form pairs in mitosis. Rather they will form homologous chromosome pairs during meiosis, which allows for crossing over to occur.
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Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division.
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A homologous chromosome pertains to one of a pair of chromosomes with the same gene sequence, loci, chromosomal length, and centromere location. A homologous pair consists of one paternal and one maternal chromosome. ... Each maternal chromosome has a corresponding paternal chromosome; they pair up during meiosis.
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When nondisjunction occurs in the first meiotic division, homologous chromosomes remain paired. This results in two daughter cells with an extra set of chromosomes and two daughter cells with no chromosomes at all. ... Fertilization of these gametes produces individuals with either too many or not enough chromosomes.
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Meiosis is a way sex cells (gametes) divide. ... In meiosis I, homologous chromosomes separate, while in meiosis II, sister chromatids separate. Meiosis II produces 4 haploid daughter cells, whereas meiosis I produces 2 diploid daughter cells. Genetic recombination (crossing over) only occurs in meiosis I.
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In metaphase I, the tetrads line themselves up at the metaphase plate and homologous pairs orient themselves randomly. In anaphase I, centromeres break down and homologous chromosomes separate. In telophase I, chromosomes move to opposite poles; during cytokinesis the cell separates into two haploid cells.
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Synapsis (also called syndesis) is the pairing of two homologous chromosomes that occurs during meiosis. It allows matching-up of homologous pairs prior to their segregation, and possible chromosomal crossover between them. Synapsis takes place during prophase I of meiosis.
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Concept 6: Meiosis I: Anaphase I. The two chromosomes in each bivalent separate and migrate toward opposite poles.