Many of the traits examined by Mendel in his dihybrid crosses are now known to b

Question

Many of the traits examined by Mendel in his dihybrid crosses are now known to be encoded by genes that occur on the same chromosome. Given the outcome of his experiments, what can you infer about the distance between these genes? How would his results have been different if the traits examined had included plant height and pod shape, which are encoded by genes that are very close together on the same chromosome?

Use the following terms in your response: alleles; loci; recombination; expected ratio.

Explanation / Answer

In dihybrid crosses, alleles responsible for two different traits are involved. Mendel proposed two important laws namely law of segregation and law of independent assortment which are helpful to understand the separation of alleles and recombination that occurs between the genes present at a particular locus on a chromosome, during cell division. The genes governing the traits chosen by Mendel were either situated far away from each other or on different chromosome. Thus, for dihybrid crosses he got the ratio as 9:3:3:1. If he had used closely situated genes for traits like plant height and pod shape then there will be very low frequency of recombination of gene and the gene will not assort independently. This would have resulted in a deviation of the expected ration (9:3:3:1).

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