Final answer:
In haploid fungi, the distance between the centromere and the gene of interest is calculated by using the frequency of recombination, which is measured in centimorgans (cM).
Step-by-step explanation:
In haploid fungi, the distance between the centromere and the gene of interest is calculated using the frequency of recombination. Geneticists use this recombination frequency to infer the genetic distance between two genes, as well as their relative order on a chromosome.
To determine this distance, you count the number of progeny that display nonparental genotypes, which are the result of crossover events between the genes of interest. The more crossovers that occur, the further apart the genes are likely to be on the chromosome, because there is a larger region over which recombination can occur. This genetic distance is measured in centimorgans (cM), named after the geneticist Thomas Hunt Morgan. One centimorgan corresponds to a 1% recombination frequency.
Therefore, if you observe that 17% of the offspring have nonparental genotypes for two specific genes, you could say that those genes are 17 cM apart. For instance, if the genes for body color and wing size recombine in 17% of offspring, they would be positioned 17 cM apart on the chromosomal map