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Title: In some fruit flies, an inversion involving the white-eyed locus (w) moves the w Post by: barry on Jul 16, 2012 In some fruit flies, an inversion involving the white-eyed locus (w) moves the w+gene from one end of the X chromosome to a location nearer to the centromere. Flies with a w+ or w+/w genotype are normally expected to have red eyes. However, in flies with the inversion, the eyes are mottled red and white. Explain why.
Title: Re: In some fruit flies, an inversion involving the white-eyed locus (w) moves the w Post by: duddy on Jul 17, 2012 The mottled phenotype is caused by a position effect. During the inversion, the w+ gene is moved from a euchromatic region on the X to a region near the heterochromatin at the centromere. Sometimes genes in this region are not transcribed because the heterochromatin remains condensed throughout the cell cycle. The eye cells in which the w+ gene has become inactivated produce white spots in the eyes. The cells in which the gene is not inactivated produce red spots.
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