Neurospora crassa is a haploid fungus. A mutant strain that requires arginine for growth (arg-) is crossed with a strain that requires tyrosine and phenylalanine (tyr-phe-). Each requirement results from a single mutation. Tests on 200 randomly collected spores from the cross give the following results: the + in any column of the table below indicates the presence of the wild-type allele of the gene.
arg tyr phe number of spores
[see table below]
a) What are the three possible two-gene recombinant frequencies? Hint: Use the table to determine the number of recombinants for each possible pair of genes. 6 pts
b) Is any linkage suggested by these data? 1 pts
Hint: A recombination frequency of nearly 50% or above suggests the absence of linkage.