Question

In the land of Salad, there are two autosomal genes that (separately) determine two unique phenotypes:

(i) Romaine lover (wild-type), Iceberg lover (Recessive);
(ii) Thousand Island dressing lover (wild-type), Balsamic Vinaigrette lover (recessive).

We use the follow abbreviations for phenotypes:

Ro = Romaine Lover;
Ice = Iceberg Lover;
TI = Thousand Island Lover;
Ba = Balsamic Lover.

Two parents, one who is a Iceberg and Balsamic lover, and the other who is Romaine, Thousand Island lover, are mated. One of the F1 offspring is back-crossed to an Iceberg, Balsamic lover. If the observed counts of each phenotype from 1000 F2 offspring are:

Ro-TI = 477;

Ro-Ba = 9;

Ice-TI = 11;

Ice-Ba = 503;

what is the estimated recombination fraction among the two genes?

Answer 1

The estimated recombination fraction among the two genes is 2.

For explanation find the below workout

Recombination frequency = Total number of recombinants/ Total number of progeny * 100.

The recombinants will be low in frequency where as the parental types will be high in frequency. So, here the recombinants are Ro-Ba = 9 and Ice-TI = 11 and the parental types are Ro-TI = 477 and Ice-Ba = 503.

So, the answer here is

= 11+9/1000*100 = 2.