In Drosophila it is easy to find out how linked genes are since that can be determined by doing experimental crosses and measuring phenotypic frequencies in the offspring (see lab 06). In addition to that, we know what genes are found in specific chromosomes (fruit flies have only four pairs of chromosomes).
But in humans it is not that straight forward. Experimental crosses are out of the question, and humans tend to have very few progeny (even large families have very few offspring compared with the potentially thousands of offspring of a couple of fruit flies).
In humans, we have to rely on pedigrees. In this lab we considered three different pedigrees showing linkage between a genetic disorder and another trait. Students learned and practiced how to identify parental and recombinant types in the offpring of each generation, and in the third exercise calculated the odds ratio to determine linkage of traits.
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