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Homework 4, calculating linkage: 1) You make a test cross from the following cross: R1 r2 / R1 r2 X r1 R2 / r1 R2

Homework 4, calculating linkage: 1) You make a test cross from the following cross: R1 r2 / R1 r2 X r1 R2 / r1 R2 You inoculate the progeny with an race that is avirulent on both genes and get 2 susceptible progeny out of 200 test cross progeny. What is the recombination distance?

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Homework 4, calculating linkage: 1) You make a test cross from the following cross: R1 r2 / R1 r2 X r1 R2 / r1 R2

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  1. Homework 4, calculating linkage: • 1) You make a test cross from the following cross: R1 r2 / R1 r2 X r1 R2 / r1 R2 • You inoculate the progeny with an race that is avirulent on both genes and get 2 susceptible progeny out of 200 test cross progeny. What is the recombination distance? • 2) You make a test cross from the following cross: R1 r2 / R1 r2 X r1 R2 / r1 R2 You inoculate the progeny with two races, Race A is virulent on R1 and avirulent on R2, Race B is avirulent on R1 and virulent on R2. You find 95 test cross progeny are resistant to race A and susceptible to race B, 101 test cross progeny that are resistant to race B and susceptible to race A, three progeny that are resistant to both races and one that is susceptible to both. B What is the recombination distance? • You find a line you think has both genes: You make a test cross with it, represented by the following cross: R1 R2 / R1 R2 X r1 r2 / r1 r2 • You inoculate the progeny with two races, Race A is virulent on R1 and avirulent on R2, Race B is avirulent on R1 and virulent on R2. You find 2 test cross progeny are resistant to race A and susceptible to race B, 4 test cross progeny that are resistant to race B and susceptible to race A, 99 progeny that are resistant to both races and 95 that are susceptible to both. B What is the recombination distance?

  2. 4) Estimate the map distance between a disease resistance gene and the DNA marker shown on the two gels below. Parent 1 (P1) is homozygous for the dominant resistance gene (R/R) and parent 2 (P2) is homozygous for the susceptible allele (r/r). The progeny are from a cross between the F1 hybrid (P1 x P2) crossed to P2. R indicates the individual is disease resistant and S indicates it is susceptible. What is you estimate of map distance between the marker and the R gene. P1 P2 F1 PROGENY R S R S R S R S S R S S R S R S R R S R MORE PROGENY S R S R S S R S S R S R S R R S R R S R R

  3. 5) Estimate the map distance between the dominant gene R, for red seed color, and the DNA marker shown on the two gels below. Parent 1 (P1) is resistant and homozygous for the dominant ‘R’ allele (genotype R/R) and parent 2 (P2) is homozygous for the recessive susceptible allele ‘r’ (r/r). The progeny are from a cross between the F1 hybrid (P1 x P2) crossed to P2. R indicates the individual is resistant. What is you restimate of map distance between the marker and the R gene. P1 P2 F1 PROGENY R S R S R S S S S R S S R S R S R R S R MORE PROGENY S R S R S S R S S R S R S R R S R R S R R

  4. Answers: move the green box after you solve. (no peeking) You Peeked! Move this box and you can see the answers Problem 1: 2% 2: 2% 3: 3% 4: 2.6% 5: 10.5 %

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