Genetic Linkage
Proof That Linked Genes Exist
-
Morgan hypothesized that alleles of two genes close together may not assort
indepentently into gametes
-
Parental arrangements may appear together in gametes
-
Performed a second cross to prove the hypothesis
-
Crossed red eye, vestigal wing (pr+pr+ vgvg)
and purple eye, normal wing flies (prpr
vg+vg+)
|
F1 Gamete
|
Testcross Distribution
|
Gamete Type
|
|
pr+ vg+
|
157
|
Recombinant
|
|
pr+ vg
|
965
|
Parental
|
|
pr vg+
|
1067
|
Parental
|
|
pr vg
|
146
|
Recombinant
|
Repulsion Cross Chi-Square Test
|
F1 Gamete
|
Observed
|
Expected
|
(O-E)2/E
|
|
pr+ vg+
|
157
|
583.75
|
312.0
|
|
pr+ vg
|
965
|
583.75
|
249.0
|
|
pr vg+
|
1067
|
583.75
|
483.3
|
|
pr vg
|
146
|
583.75
|
328.3
|
|
Total
|
2335
|
2335
|
X2=1372.6
|
