BIOL 366 Lecture Notes - Lecture 11: Sex-Determination System, Dosage Compensation, Splicing Factor
12 Mar 2018
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Document Summary
In flies y chromosome contains genes for sperm production yet not the sex determining genes sex determination depends on the number of x chromosomes. X > male gynandromorphs: male and female mosaics. Xx > female (sxl activation) gynandromorphs: differential gene expression in different body parts. Left side is female (xx) and right side is male (xo). The male side has lost an x chromosome bearing the wt alleles of eye color and wing shape, thereby allowing expression of the recessive alleles eosin eye and miniature wing on the remaining x chromosome. Drosophila: somatic sex determination and the sex- lethal gene. Sex-lethal mutants xx individual die because of failed gene dosage compensation. Sex lethal protein is a splicing factor that initiates a cascade of rna processing events that will eventually lead to male-specific and female specific transcription factors. Sex lethal gene has 2 promoters: early promoter only active in xx cells, late promoter active in both.
