Solutions For An Introduction to Genetic Analysis Chapter 17 Problem 68P

The first cross shows independent assortment for the two genes. Since two normal strains are crossed, the ascospores are also normal in color. A recombinant frequency of 50% means that the genes are unlinked and are present on separate chromosomes.

The second cross now shows that the genes are linked, since the recombination frequency is 1%. In addition, half the progeny are inviable. This data suggests the occurrence of a reciprocal translocation. Both these genes are very close to the breakpoints of the translocation.

Abnormal ad-3 x normal pan-2:

The position of the genes:

In the third cross, we see that viable spores are of two types. Half the spores contain normal chromosomes while the other half contains translocated chromosomes.