Question 3 (6 pts). In hogs, colored hair (H) is completely dominant to colorles

Question

Question 3 (6 pts). In hogs, colored hair (H) is completely dominant to colorless (h) and bent tails (B) are completely dominant to straight tails (b). There are no interlocus interactions Penetrance and expressivity are 100%. The two loci are not sex-linked. The phenotypes and frequencies of progeny following testcrosses of hogs 1 and 2 to a double recessive genotype (hh bb)are listed in the table Testcross Progeny of hog 1 134 Phenotype colored, bent colored, straight colorless, bent colorless, straight TOTALS Testcross Progeny of hog 2 28 335 358 30 751 12 143 300 a. For testcross progeny of hog 1, what are the recombinant classes or recombinant phenotypes in the progeny? b. For testcross progeny of hog 2, what are parental classes or parental phenotypes in the progeny? c. For hog 2, are the recessive alleles in the cis or trans configuration? d. (2 pts) How far apart (in cM) are the two gene loci on the genetic map? You can use data from progeny of hog 1 or hog 2. Show your work e. For hog 1, Uf the two loci were sorting or segregating independently, what fraction of the testcross progeny would you expect to have colored hair and straight tails?

Explanation / Answer

In general, in the testcross off spring on the basis of frequenices it is easy to differentitate between parental and recombinant offspring. The parental combinations are high in frequency and where as the recombinant offspring are low in frequency.
a. The categories or phenotypes with 134 and 143 are parental phenotypes where as the phenotypes with 11 and 12 are recombinants.

b. The categories or phenotypes with 335 and 358 are parental phenotypes where as the phenotypes with 28 and 30 are recombinants.

c. If both dominant genes are present on same chromosome those are reffered as cis, if one dominant and one recessive is present on same chromosome those are reffered as trans.

It the genes are arranged in cis, we can observe both dominant phenotypes and both recessive phenotypes as parental categories, if the genes are arranged in trans, the parental categories have one dominant and one recessive phenotype.

As, the hog2 parenal categories have one dominant and one recessive phenotype which means those genes are arranged in transconfiguation.

d. The distance between the genes = Total number of recombinants/ Total number of progeny X 100.

= 11+12/ 134+11+12+143 x 100 = 7.66 cMS or map units.

e. If the genes assorted independently, is follows the mendilian testcross ratio i.e 1:1:1:1.
The fraction of colore hair and straight tails will be 1/4.

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