You are investigating 4 recessive alleles in corn. They are whimpy ears (w), striped leaves (s), shriveled kernels (k), and red tassels (r). Their dominant counterparts are generally just represented by the "+" symbol. A plant that is homozygous dominant for all 4 genes is crossed with a homozygous recessive plant (ww ss kk rr). As expected, the f1 generation displays the dominant phenotypes for all 4 genes. The f1 plants are then crossed with a homozygous recessive plant for all 4 genes. A total of 1000 f2 offspring are produces. These f2 offspring display the following phenotypes:
wskr (198)
++++ (202)
wsk+ (201)
+++r (199)
w+k+ (49)
+s+r (51)
w+kr (48)
+s++ (52)
note: (no recombinants, virtually no crossing over)
a- Calculate the recombination frequencies between each of the four genes.
b- Draw a genetic map for the location of these 4 genes on the chromosome. Be sure to show the map distances between the loci.