A trait in garden peas involves the curling of leaves A dihy

A trait in garden peas involves the curling of leaves. A dihybrid cross was made involving a plant with yellow pods and curling leaves to a wild-type plant with green pods and normal leaves. All F1 offspring had green pods and normal leaves. The Fl plants were then crossed to plants with yellow pods and curling leaves. The following results were obtained: degree 117 green pods, normal leaves degree 115 yellow pods, curling leaves degree 78 green pods, curling, leaves degree 79 yellow pods, normal leaves If they are linked, calculate the map distance between the two genes. Example 20%. How accurate do you think this distance is? Show your work.

Solution

In this case the parent gametes are green pods normal leaves and yellow pods curling leaves as in dihybrid cross the genes are unlinked and the recombinants formed are almost 50% of the parent gametes so to calculate the map distance= sum of recombinant offspring/ total number of offspring

= 78+79/ 389

= 157/389= 0.4035= approximately 40% recombinant frequency.

Genrally the rf ( recombinant frequency) is 0% <rf<50% so the genes are not linked and dihybrid cross occurred accurately. Distance between two genes is more and genes are unlinked.