Question

In an attempt to create the most annoying dog in the world, a Mad GeneticistTM crosses a Yappy-dog with a Slobbery-dog. The first is pure-breeding for yappiness and no slobber, and the second is pure-breeding for slobber and no yappiness. The F1 puppies are all the neatest, quietest dogs you’ve ever seen.

a. Assuming both traits are controlled by single, unlinked genes, what are the genotypes of the parents and F1 progeny in this cross?

b. In the obvious next step, our Mad GeneticistTM crosses the F1 puppies inter se (i.e. among themselves). Show the expected genotypes and phenotypes of the F2 animals (assuming the genes are unlinked).

c. Thankfully, the total progeny of all these litters consist of 5 Yappy-puppies, 4 Slobbery-puppies, and 7 Nice Doggies, but no Yappy-Slobbery-puppies. Our geneticist wants to know whether this is just bad luck, or whether there might be some interaction between the yappy and slobbery genes such that the double-mutant animals cannot survive. You’d better find out the answer before he does: if his actual results are consistent with the theoretical expected outcome, you’ll have to kill him before he tries to breed again. Are the results he got consistent with what you’d expect from independent assortment? Show your work.

Answer 1

39 S S Sopps Xeppeo &loaps Yappines Fi XySa Nea, autek) B F2 YS 141 D Sk Ys YS yS YS YS Neat, uite Yappme 3 y S Slop 3 Yappy,Shpps 1 Thee is Sne inleradon betue 2 Dere One Pra ou Dons chi sawave Tet we nfim this Co-E Obsenes 0-E 044 2 Neak 1- 33 2 Yafp Sh 1 33 3hX3 Bth T6 OF n-1 4-1 3 785 faos at 3 The 9eno, are indapondot OSumel No lateradbn bebweer 2 sones Thums up