Mini Mouse has a red nose and Mickey Mouse has a red nose too. They had numerous children and of their F1 half of the males had black noses, half the males had red noses and all of the females had red noses!
Mini was likewise married to another mouse called Timmy. Timmy had a black nose. Mini as well as Timmy had children and half of all their F1 had black noses, the other half had red noses.
A red nose in a mouse is produced by the expression of the R gene. The R gene has one intron. In black nosed mice the R intron isn't removed since these mice are missing a SnRP. This specific SnRP is expressed in noses of red nosed mice.
Please describe these results by describing how and why introns are removed as well as proved the genotypes of Mini, Mickey and Timmy and their children