lecture_16__05 - Errors in chromosomal inheritance: In rare...

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Errors in chromosomal inheritance: In rare instances, chromosomes do not separate properly during either meiosis I or meiosis II This event, nondisjunction , generates gametes with an incorrect number of chromosomes Cells containing either less than or more than the normal haploid number of chromosomes are called aneuploid In most cases, a human fetus developing from an aneuploid gamete will not survive to term, except for the common instance of trisomy 21 which causes Down Syndrome. In this case, one of the gametes contained two copies of chromosome 21 instead of just 1. Fig. 15.11
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The genotype of a strain of diploid yeast is AaBb. A non-disjunction event occurs during meiosis such that a gamete is produced with the genotype AaB. Based on this information, when during meiosis did the non-disjunction event occur? In yeast, the products of a meiotic cycle can be isolated and characterized. If a diploid strain with the genotype AaBb sporulated and the four gametes produced during the meiosis in question were found to have the genotypes: AAB, B, ab, and ab, then you could conclude that the non-disjunction event occurred during what phase of meiosis?
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lecture_16__05 - Errors in chromosomal inheritance: In rare...

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