Question

In class we discussed that the F2 obtained from the two pure breeding lines shown in the image below is 3:1, assuming that the Rand Y locus were fully linked. rr yy x @ RR YY Rr Yy RY ry RY Rr Yy X RrYy In 200 words or fewer, tell me... 1) what phenotypic distribution you would expect to obtain in the F2 from a cross between a pure breeding plant with wrinkled yellow peas and one with smooth green peas. Briefly explain your prediction. 2) how could you use what you have learned about F2 distributions for fully linked loci to re-define the concepts of coupling and repulsive configurations? (see section 7.5 from your book).

Answer 1

1. - Pure breeding wrinkled- yellow Pure breeding smooth green peas: peas : srYY RRyy 8rYY RRyy - Pigen. ซ ? Ry - gametes Rory (smooth yellow)

Prediction in F2 is such because the genes of shape and colour are considered linked.

2. From the fact given in the question it seems that the genes for these two traits are linked and coupled together. But after solving the first question it is clear that the genes are linked but not coupled together. These are in repulsive configuration.

Copulation means tbat the genes are present on same chromosome, whereas repulsion means that the alleles are present in homologous chromosomes, not on single.

Thanks.