Final answer:
The fraction of recombinant gametes in a testcross shows the genetic distance between two genes on the chromosome, measured in centimorgans (cM). Recombination frequency helps in constructing linkage maps and determining gene inheritance patterns.
Step-by-step explanation:
The fraction of recombinant gametes in a testcross gives an idea of the physical distance between two genes on the same chromosome. The recombination frequency, which correlates with the recombination of alleles, is used to estimate the genetic distance between the genes.
A recombination frequency of 1% corresponds to a genetic distance of 1 centimorgan (cM). If we consider an example where genes A/a and B/b have a recombination frequency of 5%, this suggests that these genes are linked but far enough apart that crossovers occasionally occur. Geneticists use this information to create linkage maps indicating the relative positions of genes on chromosomes.
For instance, if the recombination frequency between two genes, representing body color and wing size, is 17%, this indicates that they are 17 cM apart, meaning that in 17% of offspring, the maternal and paternal alleles for these genes recombine. This percentage reflects the crossover frequency and helps predict how linked genes are inherited and mapped.