Question

1. You want to determine whether three prairie dog genes are linked, and if so what is the order of the genes and how many map units are they away from each other. Capital letters are dominant: L = long necked, I = short-necked, G = gray fur, g = brown fur, R = red eyes, r = pink eyes. True-breeding parentals of opposite phenotypes were bred to produce the F1 hybrids, then the F1 hybrids were test crossed to produce the following results: Long-necked, gray fur, red eyes 18 Long-necked, brown fur, red eyes 588 Long-necked, gray fur, pink eyes 101 Long-necked, brown fur, pink eyes 39 Short-necked, gray fur, red eyes 36 Short- necked, brown fur, red eyes 104 Short-necked, gray fur, pink eyes 592 Short-necked, brown fur, pink eyes 22 a. What were the parental phenotypes? b. Are the loci linked? If so, what gene is in the middle? c. Map the three genes and give the distances in map units between the three loci. 2. You cross a true-breeding parental with yellow flowers and oval petals with a true-breeding parental with purple flowers and round petals. The F1 offspring have purple flowers and oval petals. a. Give the genotypes for the parentals and F1s (you can choose your own letters for the alleles): yellow flower oval petal parental: purple flower round petal parental: _ purple flower oval petal F1: _ b. You perform a cross of the F1s, to produce the F2 generation. You get the following counts of plants of four different phenotypes. Calculate the expected counts for each phenotype. Phenotype Observed Expected Purple flower oval petals 270 Purple flower, round petals 109 Yellow flower, oval petals 97 Yellow flower, round petals 24 Total counts 500 500 c. Determine the X2 value d. How many degrees of freedom? What is the critical value?

Answer 1

parental Home Ilong LOL 36 pooj 599 ANSWERS ! 1) The gametic composition of the F, he buid ean be given as follows : | Gomete. Numbers. Type of gamete. LGR 18 double cross-over _parental single cressover blw genes L & G igre single cross-over bo genes G & R. I single crossover b/w genes G & R. L 104 I single crossover b/w genes L&G. - parentale. 22. I double cross-over a) Since the most frequently found genotypes are the parental gehsteppes, the genotype of the Fi hy breid is Late/aGre on Legg Rre. Now, since this fi hybrid receives a chremesome from each of its a pure-breeding parents, the parental phenotype and genotype are as follows ; LL gg RR => long neck, brown five, red eyes bl GG rere. » short neck gray fue pink eyes. (b). Yes, the threee leei of genes are linked . Now, since the deuble - creessover gametes occue en lowest freequency, and have the non-parental allele of the middle-gene , it can be inferred that the locus fore fue colour on the gene - G occurs in the middle.

1500 mm (@) Distance between genes L and G = 101 + 104 + 18+22x10= 245 x 100 1500 = 16-34 map units similarly, distance between genes G and a = 30 + 36 + 18+22 x 100 = 115 x1 1500 = 7.64 map unite 1500 tar tot 16.34 EM: 47.677 cm.

As per Chegg guidelines, I'm permissible to answer only the first question. Herein, I've provided the complete answer of the first question, with detailed explanation. Thanks.

1500 mm (@) Distance between genes L and G = 101 + 104 + 18+22x10= 245 x 100 1500 = 16-34 map units similarly, distance between genes G and a = 30 + 36 + 18+22 x 100 = 115 x1 1500 = 7.64 map unite 1500 tar tot 16.34 EM: 47.677 cm.