Answer to Question #339275 in Genetics for lisa

Question

(a)  Mendel did not know of the existence of chromosomes. Had he known, what change might he have made in his Principle of Independent Assortment?

(b)  Consider 4 different genes represented by a, b, c, d.  If a is linked to b, and b to c, and c to d, does it follow that a recombination experiment would detect linkage between a and d? Explain.

Answer 1

(a) If Mendel had known about the existence of chromosomes, he would have introduced into Principle of Independent Assortment that unlinked genes would be assorted independently of each other.

(b) According to the theory, genes a and d are also linked, but when conducting a recombination experiment, a single crossing over between these genes can occur, which breaks the linkage of these genes. As a result, these genes remain linked in non-recombinants, as well as in double recombinants, in which a double crossing over has occurred between these genes, which in principle is rare in the case of linked genes.