Mendelian genetic recombination of unlinked loci
Independent
assortment
of two loci (A & B)
on
separate chromosome pairs results in equal frequencies of
parental and recombinant gametes
&
individuals. Mendel crossed AABB with aabb
parents, who produce AB and ab gametes,
respectively. The F1 generation are
all AaBb. Independent assortment of the
two loci in gamete formation produces equal frequencies of
AB, Ab, aB, and ab gametes:
the AB and ab types are called parental,
and the Ab and aB are called recombinant.
Crossing the F1 with
an aabb tester strain [bottom left] allows the genotype
of the F2
progeny
to be determined directly from inspection of their phenotype,
since it is determined by the contribution of the F1
parent.