are unlinked when they are located on different chromosomes, or are far enough
apart on the same chromosome that they assort independently. On the other hand,
genes are said to be linked if they are close together on the same chromosome.
Instead of assorting independently, they are inherited together more frequently.
may occur between any pair of genes on a chromosome. The amount of crossing
over is dependent on how close the genes are located to each other, where it is
rarer for a pair of genes that are near each
other to undergo crossing over. If crossing over does not take place, the
products are parental gametes.
If crossing over does occur, then the result is recombinant gametes. The reduced
recombination that occurs between genes that are in proximity on the same
chromosome is the reason why recombinants are usually found in the lowest
Calculating recombination frequencies allows
to determine if genes linkage. Recombination frequency is
described as the frequency that a crossover event will occur between genes during meiosis. Genes positioned
on different chromosomes assort independently, having a recombination frequency
of 50%, while linked genes will have recombination frequencies less than 50%.
Another way that recombination frequencies have
been used is to build linkage
maps. These are chromosomal maps based on the calculated recombination
frequencies. Making linkage maps demonstrates
the order and relative distances between linked loci and order of linked loci
on a chromosome. A pair of genes with
a larger recombination frequency are likely farther apart, while those with a
smaller recombination frequency are likely closer together.