arg thi met, 26
arg thi +, 17
arg + met, 3
+ thi met, 56
arg + +, 51
+ thi +, 4
+ + met, 14
+ + +, 29
Map the three genes.
2. Genes a and b are linked, with 10 percent recombination. What would be the phenotypes, and the probability of each, among progeny of the following cross?
(a b+/a+ b) x (a b/a b)
(a+ means mutant while a means wild-type; the organisms are diploid, indicated by the slash)
3. Use the following two-point recombination data to map the genes concerned, and show the order and the length of the shortest intervals:
Gene loci, % recombination
a,b, 50
a,c, 15
a,d, 38
a,e, 8
b,c, 50
b,d, 13
b,e, 50
c,d, 50
c,e, 7
d,e, 45
4. One parent heterozygous for three linked alleles (C,c,Sh,sh,Bz,bz) is test-crossed with a parent homozygous for the recessive version of all three alleles (c,c,sh,sh,bz,bz)
Breeding data are shown in this table. Position the three genes on a genetic map using this information.
| Group | Genotype | Crossovers | Number | Totals |
| 1 | CShBz | None; the parentals | 479 | 952 |
| 2 | cshbz | 473 | ||
| 3 | C|shbz | Single; between C and others | 15 | 28 |
| 4 | c|ShBz | 13 | ||
| 5 | CSh|bz | Single, between Bz and others | 9 | 18 |
| 6 | csh|Bz | 9 | ||
| 7 | C|sh|Bz | Double recombinants | 1 | 2 |
| 8 | c|Sh|bz | 1 | ||
| Totals | 1000 |
