Question

A small number of type O individuals have the Bombay blood phenotype. Individuals with the Bombay blood phenotype always appear to have type O blood because they are homozygous recessive for the gene, H, which is epistatic to gene I. As long as at least one dominant H alele is present, the ABO blood type associated with the person's ABO genotype will be expressed. Individuals who are homozygous hh always have type O blood. The pedigree below includes two individuals with the Bombay blood phenotype In cavies (guinea pigs) solid-colored coats (W) are dominant to white-spoted coals (w) and short hair (L) is dominant to long hair (). Imagine genes W and L are 18 map units apart on chromosome 5. Examine the pedigree below. Note that solid-colored cavies are indicated by solid symbols and white-spotted cavies are indicated by open symbols The next two questions refer to this information Short hair Long hair AB A Short hair Long hair 8. What proportion of the gametes produced by l-1 wil be Lw gametes? a) 18% b) 41% c) 9 % d) 82 % e) none of the above AB B O Use the above information to answer the nexd two questions 6. The genotype of 1-2 is 9. The first offspring of -1 and Il-2 has a white-spotted coat. What is the probability this offspring wil also have long hair? a) rr Hh b) hh e) i HH d) i Hh e) more than one of the above is possible a) 18 % b)41% e) 9% d) 82% e) none of the above 7 What is a possible genotype for 8-17 10 If genes A and B are Sighty inked on chromosome 12, a dihybrid, Ab/lall, will produce the following gametes a) Hth b)rr Hh a) AB, all, Ab and ab in a 1:1:1:1 ratio b) ab and AlB in a 1:1 racio e) Ab and all in a 1:1 ratio d) Abab and aBlab in a 1:1 ratio e) Aallb, aaßb, Aabb and aabb in equal frequencies d) Hh e)rr hh
answeres are provided. please explain how to do them. :)

Answer 1

Epistasis: Alleles of one gene affecting alleles of another gene
In the given case, if two recessive alleles are present at the H locus, the allele status at the other locus does not exhibit their phenotype i.e. all genotypes will be OO.

6. Option D is correct
I-1 = IAIB Hh
I-2 = IAIO Hh

If one of the parents is AB, it is not possible to have progeny with the O blood group. That is possible only when both the parents carry at least one h allele.

7. Option D is correct
II-1 has to be hh.
He cannot be OO as one of his parents is AB.
So, he can be IAIA hh

8. Option B is correct
Recombination frequency = 18%
Two recombinant gametes each with 9% frequency
Parental gametes = 82%
Two parental gametes each with 41% frequency

9. Option A is correct
The probability that both genes are linked is 82%
The probability that recombination can occur = 18%