Solutions to Complementation Problems – 1) a) all of the mutants will require tryptophan for growth (trp ). is: b) In this case, since t1 is trpA– trpB+ and t2 is trpA– trpB+ the genotype of the diploid trpA- trpB+ trpA- trpB+ There are no good copies of the trpA gene, so no TrpA protein will be produced, so the resulting – diploid will be unable to synthesize tryptophan (Trp ). – + + – c) In this case, since t1 is trpA trpB and t3 is trpA trpB the genotype of the diploid is: trpA- trpB+ trpA+ trpBThere are good copies of both the trpA gene and the trpB gene, so both TrpA and TrpB proteins + will be produced, so the resulting diploid will be able to synthesize tryptophan (Trp ). d) t1 – t1 t2 t3 t4 t5 wt t2 – – t3 + + – t4 – – + – t5 + + – + – wt + + + + + + e) t6 t1 – t2 – t3 – t4 – t5 – t6 – wt – Note that, from this data, it is impossible to tell if t6 is in gene trpA or gene trpB; in either case, the results would be the same. Solutions for: 7.01 Epistasis and Complementation 1) a) Build up? m1: X m2: Y m3: Z b) Grow on? m1: Y, Z, or A m2: Z or A m3: A c) Build up? m1,m2: X m2,m3: Y m1,m3: X (the earlier of the two) d) Grow on? m1,m2: Z or A m2,m3: A m1,m3: A (the later of the two) 2) a)The pathway is: 4 C 3 A 1 2 B arginine b) m1,m4 would grow on B or arginine. 3) The pathway is: colorless compound 3 orange compound 1 yellow compound 2 4) a) There are 3 complementation groups identifying 3 genes: m1, m4, and m5 are in gene 1 m2 is in gene 2 m3, m6, m7, and m8 are in gene 3 b) No. If you isolated more mutants, you might find more genes. red compound