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AAn organized organized picture picture of the chromosomes of a human arranged arranged in pairs by size in pairs by size from largest to smallest.

PPairs 1-221-22 called AUTOSOMESAUTOSOMES

LLast pair are SEX SEX CHROMOSOMESCHROMOSOMES

2

Male - XYMale - XY

NondisjunctionNondisjunctionChromosomes may fail to separate during meiosis

Resulting gametes may have too few or too many chromosomes

Disorders:Down Syndrome – three 21st chromosomes

Turner Syndrome – single X chromosomeKlinefelter’s Syndrome – XXY chromosomes

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Down Syndrome (Trisomy 21)

Klinefelter’s Syndrome

Turners Syndrome

72n = 46

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82n = 46copyright cmassengale

92n = 47copyright cmassengale

102n = 47copyright cmassengale

112n = 47copyright cmassengale

12

2n = 45copyright cmassengale

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