Lecture 7.ppt - EUPLOID: ANEUPLOID: CHANGES IN CHROMOSOME...

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Unformatted text preview: EUPLOID: ANEUPLOID: CHANGES IN CHROMOSOME NUMBER Examples of aneuploidy NULLOSOMY: MONOSOMY: DOUBLE MONOSOMY: TRISOMY: TETRASOMY: 100,000 pregnancies Aberration 15,000 spontaneous abortions: 7,500 chromosomally abnormal 85,000 live births: 550 chromosomally abnormal Trisomy 1 0 0 2 159 0 3 53 0 4 95 0 5 0 0 6-12 561 0 13 128 17 14 275 0 15 318 0 16 1229 0 17 10 0 18 223 13 19-20 52 0 21 350 113 22 424 0 Sex chromosomes XYY 4 46 XXY 4 44 XO 1350 8 XXX 21 44 other: 2244 265 50% abnormal 0.6% abnormal Down syndrome Frequency is 1/800 live births. Affects both boys and girls. Some phenotypes: mental retardation, eyes that slant upwards and heart defects. Trisomy 21 Turner syndrome: Frequency is ~1/2500 live births. Turner woman are often short and lack ovarian development. Other features may be a webbed neck, and arms that turn out atthe elbows. monosomy for X chromosome Klinefelter syndrome: Frequency is ~1/1000 live births. Klinefelter men are often tall and lack secondary sex characteristics such as facial, underarm and pubic hair. trisomy for sex chromosomes Nondisjunction can happen either at MI or MII MI A A a a A A a a Meiosis I MII A A a a disomic nullosomic Meiosis II a a A A MI A A a a MII A A a a disomic nullosomic POLYPLOIDY: BASIC CHROMOSOME NUMBER: Karyotype of triploid bunchgrass x = 10; 3x = 30 Triploid organisms have reduced fertility due to the production of aneuploid gametes. Seedless fruits such as bananas and watermelons are due to triploidy....
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This note was uploaded on 04/21/2010 for the course BIO 89329 taught by Professor Hollingsworth during the Spring '10 term at SUNY Stony Brook.

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Lecture 7.ppt - EUPLOID: ANEUPLOID: CHANGES IN CHROMOSOME...

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