Homework Assignment #7
In maize a testcross was made to determine gene order using the three-point
method. The three loci are +/pr, +/v, and +/bm. Where + is the wild
type allele at each of the three loci. The mutant alleles are pr, v,
and bm, each at a different locus. The testcross was +/pr, +/v, +/bm
x pr/pr, v/v, bm/bm. The following progeny were
observed:
| Phenotypes
Of Offspring |
Observed
number |
| +
v bm |
230 |
| pr
+ + |
237 |
| +
+ bm |
82 |
| pr
v + |
79 |
| +
v + |
200 |
| pr
+ bm |
195 |
| pr
v bm |
44 |
| +
+ + |
42 |
| Total |
1109 |
a) Estimate the recombination fraction between
a) each pair of loci.
b) Determine which locus is between the other
b) two loci in the linear order of
the chromosome.
c) Calculate the coefficient of coincidence and
c) interference.
