1. The B and N genes are 25 map units apart on a chromosome. Following a dihybri
ID: 145378 • Letter: 1
Question
1. The B and N genes are 25 map units apart on a chromosome. Following a dihybrid testcross, how many offspring of 250 would you expect to display a recombinant phenotype? (0.5 pt) a. b. If you performed a dihybrid testcross with a cis dihybrid, what would be th genotypes of both recombinant offspring phenotypic classes? (0.5 pt) 2. Listed below are the phenotypes of the offspring from a dihybrid testcross for pollen color (coded by the C gene) and texture (coded by the T gene): Offspring phenotype orange, fuzzy pollen orange, smooth pollen yellow, fuzzy pollen yellow, smooth pollen Number of offspring 125 26 32 Which of these phenotypic groups represent the parental type (nonrecombinant)? How do you know? (1 pt) a. b. What is the recombination frequency between these linked genes? (0.5 pt) c. Draw a linkage map the the C and T genes based on this information and label the distance between them. (0.5 pt)Explanation / Answer
1) a) The phenotypic ratio in dihybrid test cross is 1:1:1:1. The percentage of recombinant is 50%. So, when 250 offsprings are formed, the recombination frequency in dihybrid test cross is,
= 250/2
= 125
b) If dihybrid test cross is performed with cis dihybrid, the genotypes of both recombinant offsprings would be half of the total recombinants (62 each).
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.