mistakes_in_meiosis

mistakes_in_meiosis - Web Animation Mistakes in Meiosis...

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Web Animation Mistakes in Meiosis After reading the text, you should be able t o... Identify the chromosomal abnormalities associated with Down syndrome, Klinefelter syndrome, and Turner syndrome. Explain what is meant by a nondisjunction. Identify three patterns in the occurrence of errors in meiosis. After viewing this animation , you should be able t o... Explain what happens when nondisjunction occurs in meiosis I. Explain what happens when nondisjunction occurs in meiosis II. Describe the results of nondisjunction in humans and in plants. NARRATION Nondisjunction in Meiosis I A diploid cell that undergoes meiosis typically produces four haploid cells, which have precisely half the genetic material of the parent cell. The diploid cell has two complete sets of chromosomes, and each of the haploid cells has a single complete set of chromosomes. Nondisjunction refers to an error in cell division. In some cases, homologous chromo- somes do not separate from each other during cell division. In other cases, the problem occurs when sister chromatids do not separate from each other. Nondisjunction can occur in mitosis or meiosis. If nondisjunction occurs in meiosis I, both chromosomes of a homologous pair migrate to the same pole, leaving one daughter cell without a chromosome. The cells go through meiosis II normally, producing four gametes with unusual numbers of chromosomes. Two gametes have one complete set of chromosomes plus one extra chromosome, indicated by n + 1. The other two gametes lack a chromosome and are designated n – 1. Exercise 1
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This note was uploaded on 12/11/2011 for the course BIO 152 taught by Professor Cordon during the Spring '07 term at University of Toronto.

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mistakes_in_meiosis - Web Animation Mistakes in Meiosis...

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