You were taking the subway to class one day and captured several family members

Question

You were taking the subway to class one day and captured several family members of an unknown rodent species on the platform. You gave them to your genetics professor to analyze, and she performed the following crosses. The F2 progeny are the result of crossing the F1 progeny to each other. 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? What are the map distances between the linked genes Male C. elegans expressing the recessive mutations l (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 1 uncoordinated, rolling 1 rolling a) Diagram the genotype of the female parent. b) Map the loci (i.e., determine the position and map distances among the genes. c) Is there evidence of interference? Justify your answer with numbers

Explanation / Answer

2) P1 are wispy whisker, pink eye, hairy female and thick whisker, brown eye and hairless male

All F1 rodents are wispy whisker, brown eye and hairy

a) Dominant traits are expressed in f1 generation.

Therefore, the dominant traits are wispy whisker, brown eye and hairy

b) The recombinant frequencies are less than 50%. So all the three genes are linked.

Parental genotypes are expressed in larger numbers. So, the parental genotypes here are wispy wisker, brown eye, hairy rodents (910) and thick wishker, 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 shifts the middle allele over the sister chromatids. Here, the gene for the eye is in the middle. Therefore, the order of genes is whisker, eye, hairy.

Distance between whisker and eye,

= 100 x (110+3+1+2) / 1600

= 100 x 116 / 1600

= 7.25 cM

Distance between eye, hairy

= 100 x (280+4+1+2) / 1600

= 100 x 287 / 1600

= 17.94 cM

Therefore, the gene map is

whisker eye hairy

I----------------------I----------------------------------------I

7.25 cM 17.94 cM

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.