Question

40 A Drosophila geneticist made a cross between females homozygous white oye color) and wild-type males. She then mated the F1 females genes y and ec? de X-linkedi recessive mutations (y, yellow body, ec, echinus eye shape: mutant males and obtained the results shown. What is the distance between Females + + + / ew ye /yee w ++/yow + ec w/yec y + w/yew + e + c ++ wly +/yor a 24/1009 X 100 CM 41/1009 X 100 CM 66/1009 X 100 CM 68/1009 X 100 CM 18944/1209 X 100 CM

genetics

Answer 1

Cross made between y Fi fanale = y ee we fi q crossed to y ee we (male) we Calculate We need to find distance b/w y and ce. If we can find recombination free b/w these 2 genes, we can calculate distance. | Recombr forquency. - no. of recombinants x 100 Total Offsprings Here, we need to find no. of single cross over blu. y and ec genes (ie, recombinant). male parent t ,t t * Cross over can only occur y ee w in female. + as + 3 - » & ec w 4 + t l g. Recombinant I gametes by I when fertilised with Penale) y ec e Chromosome of & malé parent , Progeny obtained = + ec w l y ec ne y t t 1 y ec w And double Cross over progeny also have single tross Over b/w y and ec. d

Cross Overs. Smallest no as no. Senas are double offsprings are of lot 11+ 2+1 x 100 1009 Recomb OLA freq - 34 x 10 cm. 1007