Question

1. The following ordered tetrads were obtained by crossing a strain of Neurospora requiring histadine with a strain requiring phenylalanine. (Use the data to answer 1-4). А his h is his to his phe his phe phe $ phe his to his phe his phe poi phe his oth his t h is phe + phe op phe ething to his phe a rethe phe his file + phe ob + phe oth + olio of his $o ele + Total = 100 68 What is the map distance from phenylalanine to its centromere? a 15.0 b. 10.5 c. 30.0 e. 15.5 2. What is the map distance between the histidine and its centromere? a. 9.0 b. 8.5 c. 13.0 d. 6.5 e. 16.0 Vopoor 3. What is the map distance between histidine and phenylalanine? a. 15.0 D. 21.5 c. 21 d. 8.5 e. 10.5 4. Map the two loci and the centromere. Between which two elements did the crossover(s) in ascus "F" occur? a. centromere and his b. centromere and phe c. phe and his d. none of above

Answer 1

+ + Phe + + Phe Phe Phe Phe + Phe + Phe Phe + Phet the the Phe Phe + + + Phe + + ī 5 IL E 68 FDSP 7 SDSP SDSP SDSP fost SDSP FOSP S FDSP= first Division seggregation pattern 2 SDSP = Second Division seggregation pattern , Distance between centromere to phenylalanine ² (No. of ascus with SDSP) Total = £x (7+5+7+11) xico XICO 100 = + x 30 = 15cm 2. A B his his + his his his + E + his his + 3+ + his + his his + + his + 5+ } } the + his his 8 + + + lit bis = 68 fosP FOSP FDSP SDSP FDSP SDSP SDSP Distance b/w Centromere to histidline = (No. of ascus with sosp Total --X100 = + (1+1+ x100 = 1/x 13 = 6.5cm - 160

3. his phe + Phe + Phe his the + Phe T hist hist his the hist hist + + Phe + Phe hist + + + + 7 PD TT PD = Parental Ditype a 100% parental NPD = Non- Parental Ditype 100% non-parental TT = Tetratype (TT) 50% Parental & 50% Recombinant Distance between the & His = + (No. of TT) + (No. of APD X1W Total = $(7+5+1 +7+1) + Oxid 160 = 2 x 21 = 10. 5cm + + After + +11+ = 11 Crossing +111 +TI Meiasis I over 15cm between Centromere & Histidin (Parental) (S-phase) MIL In ascus 'f' Crossing over occur between centromere & His so, oftich (a) is conect. F' ascus