MCB164+ICE3key

MCB164+ICE3key - st -/- is fully epistatic to bt-/-(i.e....

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MCB 164 S09 Names of group members April 27 2009 In class exercise #3 Score: Key 1. You have created a mouse model for “shrunken toenail syndrome” and find that two genes act in a simple enzymatic pathway to create smooth toenails, BLUETOE (BT ) and SHRUNKEN TOENAIL (ST ). A bt -/- null mutant has smooth blue toenails and a st -/- null has white shrunken toenails. ST BT A B C You cross 2 mice heterozygous for both genes. Po bt -/+ ; st -/+ X bt -/+ ; st -/+ Indicate what fraction of F1 progeny will exhibit the phenotypes listed below. Assume that null alleles are recessive to wild type and that
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Unformatted text preview: st -/- is fully epistatic to bt-/-(i.e. bt-/-; st -/- animals have white shrunken toenails). Smooth white: bt +_ ; st +/_ (3/4) x (3/4) = 9/16 Smooth blue: bt-/-; st +_ (1/4) (3/4) = 3/16 Shrunken white: bt any ; st -/- (1/4) = 4/16 Shrunken blue: 0 2. You find a dominant gain-of-function allele of BT that gives purple toenails ( bt D ) . Based on the pathway shown above, predict the phenotype of a bt D/+ ; st -/-a) shrunken white b) shrunken purple c) shrunken blue d) nonshrunken white e) nonshrunken purple f) nonshrunken blue...
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