9A-Chromosomes-VARIATION

9A-Chromosomes-VARIA - Chromosome Variation pp 235 260 Chromosomal Mutations individual chromosome loses or gains parts sequence of individual

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Chromosome Variation pp. 235 - 260 Chromosomal Mutations o individual chromosome loses or gains parts o sequence of individual genes is altered o change in the number of chromosomes Types of Chromosomal Mutations o Changes in chromosome number Aneuploidy Polyploidy o Chromosomal rearrangements Aneuploidy o changes in the number of individual chromosomes o several causes loss during mitosis or meiosis (i.e. deletion of centromere) nondisjunction Types of Aneuploidy o Nullisomy 2n – 2 o Monosomy 2n – 1 o Trisomy 2n + 1 o Tetrasomy 2n + 2 Aneuploidy in Humans o unusual less than 2% of all fetuses survive
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o Sex-chromosome aneuploids much better tolerated so most common Turner, Klinefelter syndromes o Autosomal aneuploids Trisomy 21 Down syndrome Trisomy 18 Edward syndrome Trisomy 13 Patau syndrome Polyploidy o the presence of one or more additional sets of chromosomes triploids (3x) tetraploids (4x) pentaploids (5x) o Very common in plants
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This note was uploaded on 05/01/2008 for the course BSCI 222 taught by Professor Gdovin during the Spring '08 term at Maryland.

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9A-Chromosomes-VARIA - Chromosome Variation pp 235 260 Chromosomal Mutations individual chromosome loses or gains parts sequence of individual

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