Question

P1: wispy whisker, pink eye, hairy female #1 x thick whisker, brown eye, hairless male #A F1: all wispy whisker, brown eye, hairy rodents F2: 910 wispy whisker, brown eye, hairy rodents 290 thick whisker, brown eye, hairless rodents 110 thick whisker, pink eye, hairless rodents 280 wispy whisker, pink eye, hairy rodents 3 wispy whisker, brown eye, hairless rodents 4 thick whisker, brown eye, hairy rodents 1 wispy whisker, pink eye, hairless rodents 2 thick whisker, pink eye, hairy rodents a) What are the dominance patterns of the traits? b) What are the genotypes of each parental group? Which, if any, of the genes are linked? W are the map distances between the linked genes 3) (12 pts) Male C.elegans expressing the recessive mutations I (long),r (rolling), t (touch insensitive), and u (uncoordinated) are crossed to phenotypically wild-type females. The phenotypes of the 3288 F2 progeny are shown below. 653 uncoordinated, long, rolling, touch insensitive 670 long, rolling, touch insensitive 675 wild type 655 uncoordinated 73 uncoordinated, long 71 long 73 uncoordinated, rolling, touch insensitive 74 rolling, touch insensitive 88 uncoordinated, long, rolling 83 long, rolling 85 uncoordinated, touch insensitive 84 touch insensitive 1 uncoordinated, long, touch insensitive 1 long, touch insensitive uncoordinated, rolling rolling a) Diagram the genotype of the female parent. b) Map the loci (i.e., determine the position and map distances among the genes). lu there eyidence of interference? Justify your answer with numbers.

Answer 1

2.

P1 =wispy whisker, pink eye, hairy female × thick whisker, brown eye, hairless male
F1- all wispy whisker, brown eye, hairy
a)Ans-
Dominant traits are expressed in F1 generation. Therefore, the dominant traits are wispy whisker, brown eye and hairy.
b) Ans-
Since there are less than 50 % recombinant frequencies, so all the three genes are linked.
Parental genotypes are expressed in large numbers. So, the parental genotypes here are
wispy whisker, brown eye, hairy rodents(910) and
thick whisker, brown eye, hairless rodents (290)
Double recombinants are present in lowest numbers. Therefore, the double recombinants here are wispy whisker, pink eye, hairless rodents and thick whisker, pink eye, hairy rodents.
Double recombination moves the middle allele over the sister chromatids and the gene for the eye is in the middle. Therefore, the order of genes
whisker, eye, hairy
The distance between whisker and eye gene
= 100 × (110+3+1+2)/1600
=100× 116/1600
= 7.25 cM
The distance between the eye and hairy genes
= 100 × (280+ 4+ 1+ 2)/1600
= 100 × 287/1600
=17.94 cM
Therefore, the gene map is
Whisker eye hairy
I--------------------------I---------------------------------------------------I
        7.25 cM              17.94 cM