MCB164+S09+ICE1KEY - tra-1 XX hermaphrodite NA XO male...

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MCB164 S09 Names of group members:_____ _______________________ April 2 2009 In class exercise #1 _____________________________ Score: ____KEY______ _____________________________ Sex is determined by the X chromosome to autosome ratio (XX:AA) in C. elegans . When the ratio is 1.0 the worm is hermaphrodite. When the ratio is 0.5 the worm is male. tra-1 is a gene required for hermaphrodite development. A recessive, loss of function mutation tra-1(e1099) transforms XX animals to males. A dominant, gain of function mutation tra-1(e1575) transforms XX and XO animal to female. All mutants are fertile. Allele Phenotype Dom./ Rec. compared with wild type
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Unformatted text preview: tra-1 XX hermaphrodite NA XO male tra-1(e1575) XX female dominant XO female dominant tra-1(e1099) XX male recessive XO male recessive ______________________________________________________ Consider the following cross: Po XX tra-1 (e1575)/tra-1(wild type) X XO tra-1 (e1099) / tra-1(e1099) A. What is the phenotype of the XX tra-1 (e1575)/tra-1(wild type ) heterozygote? Circle one Male Female Hermaphrodite B. What fraction of F1 progeny will be male? Circle one All ½ ¼ none C. Which sex do you think the tra-1 gene is normally expressed? Circle one Hermaphrodite Male...
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