Chapter 11

Chapter 11 - Chapter 11 Chromosome Mutations Multiples of...

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Chapter 11 Chromosome Mutations Multiples of complete sets of chromosomes are called polyploidy. Even numbers are usually fertile. Odd numbers are usually sterile. Aneuploidy refers to the gain or loss of single chromosomes, usually in meiosis. Chromosome aberrations include translocations, inversion, deletion, duplication. Each has characteristic meiotic pairing. Crossing-over may result in abnormal gametes, reduced fertility and unmasking of deleterious recessive alleles. Duplication can also provide material for evolutionary divergence. Chromosome mutations Two major types change in number of copies of chromosomes alteration of chromosome structure Aberrant euploidy Changes in whole chromosome sets Euploidy: multiples of basic chromosome set Haploid/diploid Aberrant euploid: more or less than normal number monoploid (1 n ) triploid (3 n ) Monoploidy Male bees, wasps, ants parthenogenetic development of unfertilized egg single set of chromosomes produce gametes by mitosis Usually lethal in other systems unmasks recessive lethals if individual survives to adulthood, no meiosis, sterility Polyploidy Very common in plants associated with origin of new species may positively correlate to size of individual
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Chapter 11 - Chapter 11 Chromosome Mutations Multiples of...

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