CHROMOSOME MAPPING

=Chromosome Mapping= In the previous example [see recombinant frequencies] we figured out that the original parental arrangement of the genes was Ab and aB. This also means that the gametes containing the combinations AB or ab were the result of crossing over. [image:http://i.imgur.com/YcwFW3h.png?1] The crossing over value represents how often crossing over occurs between the two genes. As we discussed earlier, the further apart the two genes are, the more likely that crossing over will occur somewhere in-between the two. Conversely, the closer the two genes are together, the less likely crossing over is likely to occur between the two. Thus the crossover value gives us an indication of the physical distance between the two genes. Using this information, we can construct a ‘map’ of the chromosome. A chromosome map simply shows the distance between two or more locations, referred to as loci, on the chromosome. The above example is simple as it only involves two loci. Note that, instead of a %, we simply put m.u. (map units). [image:http://i.imgur.com/yWmJpkH.png] Let's try another, slightly more complicated example... [image:http://i.imgur.com/6EIrUpz.png?1]