Question

4. You are studying three genes in corn and performed a three-point cross. The three genes are green (V) vs Viniscent (V) seedlings, blue (Pr) vs red kernels (pr) and white (B ) or brown (bm) leaf midrib color. The table below list the offspring resulting from a testcross with a female F1 heterozygote. Type of gamete (NR, SCO, DCO Phenotype Progeny Gamete from F1 heterozygote Virescent seedling red 101 kernel Red kernel 175 Red kernel, brown midrib 259 Virescent seedling 263 Virescent seedling red lernel, brown midrib Virescent seedling brown midrib brown midrib 119 Wild-type Progeny total a Which of the three genes on the chromosome is in the middle? b. Write the genotype of the heterozygous parent, as the alleles appear on chromosomes in the correct order. Calculate the recombination frequency for each gene pair (show your work for full credit). Draw a map of the chromosome region with the distance between each gene marked in map units. d. Calculate the coefficient of coincidence. Is there interference? If so, what is the value?

Answer 1

Phenotypes Virescent seedling, progeny 101 Camere from If heterozygote pr v Bm type of gamere. sco (b/n Pr & V) Seo (bln V& 175 Bm) pr v Bm por v bm 259 red kernel. Red kernel Red kernel, brown midrib. Vinescent seedling Virescent seedling, red kernel, brown NR (highest NR (highest 263 Pr v Bm. number) 53 prvom DCO< Double Cross over? lowest number sco (bln Vf Bm ) 181 Pr v bm midrib virescent seedling brown midrib on Brown midrib 7) sco (b/n Pr & Pr v bm 119 49 Pr v Bm double Cross over.(DLO) Howest number wild type

Ans-a and Vito come Genes In for the the mid mbinan changed the double cros a position pattern for the for the men (V) and viriscent seedlings are present the middle of the chromosome. When we compane able crossover with the nonrecombinant only the green and uniscent gene is changed green pr o V bm v bm (viniscent, red will toe seedling . O'kemel, brown V Bm. midrib) X X PY Pr v Bm wild type Ansb :- Genotype of the heterozygous parent → Po V Bm / px V bm. Por v Bm green seedling (Rev) is found on recessive genes el red kernels - pr v bm. genes for the green seedling (PV) one chromosome with two recessive genes bored and brown midrib (prv bm) and genes for the visiscent seedling (w), blue kerenels white (Bm) midrib are found together (Pr v Bm) and brown to visiscent see und togeth Ans.co Recombination frequency between for and we - Single cross over bin fr andre + DCO genes 100 Total - 101 + 119 +53 +49 x 100 26.83 mapunit 1200 Recombination frequency between wand bm genes. - Progeny oblained by sco between V and bm +DCO... nd bm +Dco x 200 Toral = 175 + 181 +33+ 49. -xlov = 38.17 map unit 12.00

map of chromosome (Bm/om) (Pr/pr) (w/v) € 26.83 mut 38.17 mu 65 mu Ans.d = Expected rate of double recombination = Recombination between & Recombination frequency Por and u between V and Bm 322 X 458 = 0.2683 7 0.3817 R00 = 0.1024 given number of double recombinants = 49+5 3 = 0.085 1200 Coefficient of in coincidence = acheal frequency of double recombinants Expected frequency of double recombinants 0.085 0.1024 - 018301 = 0.83 Interference = 1- Coc Coeld of coincidence? 2 1 - 0.8301 = 0.1699 = 0.17 or 17%