Question

In flying pigs, genes for wing length (S = long wings, s = short wings) and body color (P=gray; p = pink) are 24 map units apart. You are crossing a dihybrid male pig (created by crossing a pure-breeding short-winged gray pig with a pure-breeding long-winged pink pig) with a pink, short-winged female pig. For the questions that follow, where appropriate, do not do the math -- report individual chances and mathematical operators. Are the male pigs alleles in cis or trans? trans These pigs produce a pink piglet. What is the chance that it also has short wings? 24 What is the chance that they have two piglets - one pink with long wings and the other gray with short wings? [(1/2*0.76)*(1/2*0.7 Very briefly explain each element that you included in your calculation of chance for the two piglets (in the order that you entered them above). There is a half chanc Answer 1: trans

explain

Answer 1

Given:
S = Long wings are dominant to s = Short Wings
P = Grey is dominant to p = pink

Now, the dihybrid male pig was made by crossing:

Pure breeding short-winged, Grey pig (ssPP) with pure breeding long-winged, pink pig (SSpp)

As these two strains are pure breeding, they are Homozygous for the mentioned phenotypes. These two pigs are crossed to produce a Dihybrid male with Genotype sP/Sp.

Now, one of the chromosomes of this dihybrid is sP and the other is Sp, since one parent contributes the sP gamete and the other parent contributes is Sp gamete. Therefore, both Dominant alleles are on homologous chromosomes. Therefore, the alleles in the pig are in trans.

The Dihybrid pig is crossed with a pink, short-winged female.

sP/Sp x sp/sp

Since the two loci are 24 map units apart, the recombination frequency between the two loci is 24%. A pink piglet with short wings is produced, when there is crossing over between the two loci in the Male dihybrid, producing SP and sp gametes. These two gametes, together, represent 24% of all gametes generated.

Therefore, 12% of gametes are sp; which produce Pink, short-winged piglets. Therefore, the chance of a pink, short-winged piglet is 0.12

Chance of one piglet that is pink, with long wings and another Grey with short wings
    = Frequency of Sp gamete * Frequency of sP gamete
    = 0.38 * 0.38 = 0.1444